Mexico–United States border

File:Algodones sand-dune-fence.jpg at Algodones Sand Dunes, California. The fence on the U.S.–Mexican border is a special construction of narrow, {{convert|15|ft|abbr=on|order=flip}} tall elements, that are movable vertically. This way, they can be lifted on top of the ever shifting sand dunes.]]

The Mexico–United States border extends {{convert|3,145|km|mi|abbr=off|sp=us}}, in addition to the maritime boundaries of {{convert|29|km|mi|abbr=on}} into the Pacific Ocean and {{convert|19|km|mi|abbr=on}} into the Gulf of Mexico.{{cite web |url=http://faolex.fao.org/docs/pdf/bi-51757.pdf |title=Treaty to Resolve Pending Boundary Differences and Maintain the Rio Grande and Colorado River as the International Boundary between the United States of America and México |date=November 23, 1970 |access-date=December 7, 2014}}{{cite journal |last=McCarthy |first=Robert J. |date=Spring 2011 |title=Executive Authority, Adaptive Treaty Interpretation, and the International Boundary and Water Commission, U.S.–Mexico |journal=Water Law Review |pages=3–5 |ssrn=1839903}} It is the tenth-longest border between two countries in the world.{{Cite web |url=https://www.worldatlas.com/articles/countries-with-the-longest-land-borders.html |title=Countries With the Longest Land Borders |website=WorldAtlas |date=August 2019 |language=en |access-date=November 1, 2019}}

The Mexico–U.S. border begins at the Initial Point of Boundary Between U.S. and Mexico, which is set one marine league (three nautical miles) south of the southernmost point of San Diego Bay. The border then proceeds for {{convert|227|km|mi|abbr=on}} in a straight line towards the confluence of the Colorado River and Gila River.{{Cite web |url=https://sandiegohistory.org/journal/v54-1/pdf/Levanetz.pdf |title=A Compromised Country: Redefining the U.S.-Mexico Border |last=Levanetz |first=Joel |website=San Diego History Center |access-date=August 27, 2019}} The border continues southwards along the Colorado River for {{convert|39|km|mi|abbr=on|sp=us}}, until it reaches a point {{convert|20.|mi|abbr=on|order=flip}} south of the Gila River confluence. The border then follows a series of lines and parallels totaling {{convert|859|km|mi|abbr=on}}. First, it follows a straight line from the Colorado River to the intersection of the 31° 20′ parallel north and the 111th meridian west. It then proceeds eastwards along the 31° 20′ parallel north up to a meridian {{convert|100.|mi|abbr=on|order=flip}} west of the point where the Rio Grande crosses the 31° 47′ parallel north, It then proceeds northwards along that meridian up to the 31° 47′ parallel north and then eastwards along that parallel until it meets the Rio Grande.{{Cite web |url=https://www.library.pima.gov/content/gadsden-purchase/ |title=Gadsden Purchase |website=Pima County Public Library |language=en-US |access-date=August 30, 2019}}

According to the International Boundary and Water Commission, the continental border then follows the middle of the Rio Grande—according to the 1848 Treaty of Guadalupe Hidalgo between the two nations, "along the deepest channel" (also known as the thalweg)—a distance of {{convert|2,020.|km|mi|abbr=on}} to its mouth at the Gulf of Mexico.{{cite web |url=http://www.ibwc.gov/Files/US-Mx_Boundary_Map.pdf |title=United States Section Directive |access-date=November 11, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20111015035847/http://ibwc.gov/Files/US-Mx_Boundary_Map.pdf |archive-date=October 15, 2011}} The Rio Grande frequently meanders along the Texas–Mexico border. As a result, the U.S. and Mexico have a treaty by which the Rio Grande is maintained as the border, with new cut-offs and islands being transferred to the other nation as necessary. The Boundary Treaty of 1970 between Mexico and the U.S. settled all outstanding boundary disputes and uncertainties related to the Rio Grande border.

The U.S. states along the border, from west to east, are California, Arizona, New Mexico, and Texas. The Mexican states along the border are Baja California, Sonora, Chihuahua, Coahuila, Nuevo León, and Tamaulipas. Among the U.S. states, Texas has the longest stretch of the border with Mexico, while California has the shortest. Among the states in Mexico, Chihuahua has the longest border with the U.S., while Nuevo León has the shortest. Along the border are 23 U.S. counties and 39 Mexican municipalities.

File:Patrolling Rio Grande @ Laredo.jpg|Border Patrol patrolling the Rio Grande in an airboat in Laredo, Texas

File:USA Mexico border New Mexico.JPG|The start of the border fence in the state of New Mexico{{snd}}just west of El Paso, Texas

File:El Camino del Diablo, border patrol.jpg|U.S. Border Patrol helicopter along El Camino del Diablo, Arizona–Sonora border, 2004

File:Mexican-American border at Nogales.jpg|Border between Nogales, Arizona, on the left, and Nogales, Sonora, on the right

File:US-Mexico-Nogales-Border.jpg|On the left: Nogales, Arizona; on the right, Nogales, Sonora

File:Borderbeachtj.jpg|Beach in Tijuana at the border in 2006

File:Border Patrol Vehicle near U.S. Mexico Border.jpg|A CBP Border Patrol vehicle sitting near Mexico–U.S. border

File:View of CBX bridge from parking lot on U.S. side.jpg|View of the Cross Border Xpress (CBX) bridge from parking lot on U.S. side, with Tijuana Airport on the left and the CBX U.S. terminal on the right

File:Adams onis map.png

In the mid-16th century, after the discovery of silver, settlers from various countries and backgrounds began to arrive in the area. This period of sparse settlement included colonizers from different backgrounds. The area was part of New Spain. In the early 19th century, the U.S. bought the lands known as the Louisiana Purchase from France and began to expand steadily westward.{{cite book |url=https://archive.org/details/troublesomeborde00osca_0 |url-access=registration |title=Troublesome Border |last=Martínez |first=Oscar J. |publisher=University of Arizona Press |year=1988 |isbn=978-0-8165-1104-4 |location=Tucson}}

After the 1803 Louisiana Purchase, the border between the U.S. and New Spain was not clearly defined. The border was established in the 1819 Adams–Onís Treaty between the U.S. and Spain, which specified northern and eastern borders. Mexico gained its independence from Spain, and the border was reaffirmed in the 1828 Treaty of Limits.

Mexico attempted to create a buffer zone at the border that would prevent possible invasion from the north. The Mexican government encouraged thousands of their own citizens to settle in the region that is now known as Texas and even offered inexpensive land to settlers from the U.S. in exchange for populating the area. The influx of people did not provide the defense that Mexico had hoped for and instead Texas declared its independence in 1836, which lasted until 1845 when the U.S. annexed it.

File:San Diego-Tijuana JPLLandsat.jpg together with Tijuana creates the bi-national San Diego–Tijuana metropolitan area]]

The constant conflicts in the Texas region in the mid-19th century eventually led to the Mexican–American War, which began in 1846 and ended in 1848 with the Treaty of Guadalupe Hidalgo. In the terms of the peace treaty, Mexico lost more than {{convert|2,500,000|sqkm|sqmi|abbr=|sp=us}} of land, 55%{{cite web |url=http://www.ourdocuments.gov/doc.php?flash=true&doc=26 |title=Treaty of Guadalupe Hidalgo |year=1848 |website=Ourdocuments.gov |access-date=December 6, 2014}} of its territory, including all of what is today California, Arizona, New Mexico, Utah, Nevada and parts of what is Colorado, Wyoming, Kansas, and Oklahoma. In addition, all disputes over Texas and the disputed territory between Rio Grande and Rio Nueces were abandoned. The exact border was established by surveyors from both countries, who interpreted the treaty as they completed the United States and Mexican Boundary Survey.

Five years later, the Gadsden Purchase completed the creation of the current U.S.–Mexico border. The purchase was initially to accommodate a planned railway right-of-way. These purchases left approximately 300,000 people living in the once disputed lands, many of whom were Mexican nationals. Following the establishment of the current border, several towns sprang up along this boundary, and many of the Mexican citizens were given free land in the northern regions of Mexico in exchange for returning and repopulating the area.{{cite book |title=The Late Great Mexican Border: Reports from a Disappearing Line |publisher=Cinco Puntos Press |year=1996 |isbn=978-0-938317-24-1 |editor1-last=Byrd |editor1-first=Bobby |location=El Paso |editor2-last=Mississippi |editor2-first=Susannah}}

{{See also|Rio Grande border disputes}}

File:ISS067-E-174541 El Paso and Juárez.jpg (left) and Ciudad Juárez, Chihuahua (right), taken on June 30, 2022, from the International Space Station with north oriented towards the bottom-left side. The Rio Grande appears as a thin line separating the two cities through the middle of the photograph. El Paso and Juarez make up the third largest U.S. international metroplex after Detroit–Windsor and San Diego–Tijuana.]]

The Treaty of Guadalupe Hidalgo and another treaty in 1884 were the agreements originally responsible for the settlement of the international border, both of which specified that the middle of the Rio Grande was the border, irrespective of any alterations in the channels or banks. The Rio Grande shifted south between 1852 and 1868, with the most radical shift in the river occurring after a flood in 1864. By 1873 the moving river-center border had cut off approximately {{convert|2.4|km2|acres|abbr=|sp=us}} of Mexican territory in the El Paso-Juarez area, in effect transferring the land to the U.S.. By a treaty negotiated in 1963, Mexico regained most of this land in what became known as the Chamizal dispute and transferred {{convert|1.07|km2|acres|abbr=on}} in return to the U.S. Border treaties are jointly administered by the International Boundary and Water Commission (IBWC), which was established in 1889 to maintain the border, allocate river waters between the two nations, and provide for flood control and water sanitation. Once viewed as a model of international cooperation, in recent decades the IBWC has been heavily criticized as an institutional anachronism, by-passed by modern social, environmental and political issues. In particular, jurisdictional issues regarding water rights in the Rio Grande Valley have continued to cause tension between farmers along the border, according to Mexican political scientist Armand Peschard-Sverdrup.{{cite book |last1=Peschard-Sverdrup |first1=Armand |title=U.S.-Mexico Transboundary Water Management: The Case of the Rio Grande/Rio Bravo |year=2003 |publisher=Center for Strategic & International Studies |isbn=978-0-89206-424-3 |edition=1}}{{cite news |title=Water Rights War Rages on Faltering Rio Grande |url=https://www.nytimes.com/2002/04/19/us/water-rights-war-rages-on-faltering-rio-grande.html |date=2002-04-19 |work=The New York Times |last1=Yardley |first1=Jim |access-date=April 5, 2020}}

The economic development of the border region on the Mexican side of the border depended largely on its proximity to the U.S., because of its remoteness from commercial centers in Mexico. During the years of Mexican President Porfirio Díaz, between 1876 and 1910, the border communities boomed because of close ties to the U.S. and the Mexican government's support for financial investments from the U.S.{{cite book |url=https://archive.org/details/isbn_9780195112283/page/433 |title=Oxford History of Mexico |last=Hart |first=John M. |publisher=Oxford University Press |year=2000 |isbn=978-0-19-511228-3 |location=New York |pages=[https://archive.org/details/isbn_9780195112283/page/433 433–466] |chapter=The Mexican Revolution, 1910–1920}} Railroads were built that connected the northern Mexican states more to the U.S. than to Mexico, and the population grew tremendously. The mining industry also developed, as did the U.S.'s control of it. By the early 20th century companies from the U.S. controlled 81% of the mining industry and had invested US$500 million in the Mexican economy overall, 25% of it in the border regions.{{cite book |title=The U.S.-Mexican Border in the Twentieth Century |url=https://archive.org/details/usmexicanborderi0000lore |url-access=registration |last=Lorey |first=David E. |publisher=Scholarly Resources, Inc. |year=1999 |isbn=978-0-8420-2756-4 |location=Wilmington}}

File:Border barrier near IBM 9.JPG

The U.S. Immigration Act of 1891 authorized the implementation of inspection stations at ports of entry along the Mexican and Canadian borders. The U.S. Immigration Act of 1917 required the passing of a literacy test and a head tax by Mexicans wanting to enter the U.S. legally; however, during World War I, when labor shortages grew, the provisions were temporarily suspended. The U.S. Immigration Act of 1924 established the U.S. Border Patrol.{{Cite journal |date=1999 |title=Some Events in the History of Mexico and the Border |journal=The Journal of American History |volume=86 |issue=2 |pages=453–454 |doi=10.2307/2567039 |jstor=2567039}}

The Mexican Revolution, caused at least partially by animosity toward foreign ownership of Mexican properties, began in 1910. The revolution increased the political instability in Mexico but did not significantly slow U.S. investment. It did reduce economic development within Mexico, however, and the border regions reflected this. As the infrastructure of communities on the U.S. side continued to improve, the Mexican side began to fall behind in the construction and maintenance of important transportation networks and systems necessary to municipal development.

Although the Mexican Revolution caused insecurity in Mexico, it also strained U.S.–Mexico relations. With the Mexican Revolution lasting for 10 years, ending in 1920, and World War I simultaneously occurring between 1914 and 1918, the division between the U.S. and Mexico began to polarize the two nations. Constant battles and raids along the border made both authorities nervous about borderland security. The Zimmerman Telegram, a diplomatic cable sent by Germany but intercepted and decrypted by British intelligence, was meant to bait Mexico into war with the U.S. in order to reconquer what was taken from them during the Mexican-American War. This inspired the U.S. Federal Bureau of Investigation to monitor suspicious activities and potential violence at the border.{{Cite journal |last=Sherman |first=John W. |date=Fall 2016 |title=Fascist 'Gold Shirts' on the Río Grande: Borderlands Intrigue in the Time of Lázaro Cárdenas |journal=Journal of South Texas |volume=30 |pages=8–21}} Within 10 years, frequent provocations caused border towns to transform into battlefields, which intensified transborder restrictions, brought federal soldiers to patrol the border, and caused the construction of fences and barriers between border towns. When the battles concluded, restrictions for crossing the border were relaxed and most soldiers were sent home; however, the fences remained as a physical reminder of the division between the two nations. As years passed, more fences and higher barriers were established as attentions focused on the boundary demarcation between the U.S. and Mexico.{{Cite book |title=Line in the Sand: A History of the Western U.S.-Mexico Border |url=https://archive.org/details/linesandhistoryw00john |url-access=limited |last=St. John |first=Rachel |publisher=Princeton, NJ: Princeton University Press |year=2011 |isbn=978-0-691-15613-2 |pages=[https://archive.org/details/linesandhistoryw00john/page/n16 4]}}

The first international bridge was the Brownsville & Matamoros International Bridge built in 1910. The first barrier built by the U.S. was between 1909 and 1911 in California, the first barrier built by Mexico was likely in 1918; barriers were extended in the 1920s and 1940s.{{cite web |last1=John |first1=Rachel St |title=The Raging Controversy at the Border Began With This Incident 100 Years Ago |url=https://www.smithsonianmag.com/history/raging-controversy-border-began-100-years-ago-180969343/ |website=Smithsonian Magazine |language=en}}

The Banco Convention of 1905 between the U.S. and Mexico allowed, in the event of sudden changes in the course of the Rio Grande (as by flooding), for the border to be altered to follow the new course.{{cite web |url=http://www.ibwc.state.gov/Files/Convention_of_1905.pdf |title=Convention Between the United States and Mexico for the Elimination of the Bancos in the Rio Grande from the Effects of Article II of the Treaty of November 12, 1884 |date=June 5, 1907 |access-date=April 19, 2015 |url-status=dead |archive-url=https://web.archive.org/web/20151009042029/http://www.ibwc.state.gov/Files/Convention_of_1905.pdf |archive-date=October 9, 2015}} The sudden changes often created bancos (land surrounded by bends in the river that became segregated from either country by a cutoff, often caused by rapid accretion or avulsion of the alluvial channel), especially in the lower Rio Grande Valley. When these bancos are created, the International Boundary and Water Commission investigates if land previously belonging to the U.S. or Mexico is to be considered on the other side of the border.{{cite web |last=Metz |first=Leon C. |date=June 12, 2010 |title=Bancos of the Rio Grande |url=https://www.tshaonline.org/handbook/online/articles/rnb08 |work=Handbook of Texas Online |publisher=Texas State Historical Association |access-date=July 13, 2015 |archive-url=https://web.archive.org/web/20161027194705/https://www.tshaonline.org/handbook/online/articles/rnb08%29 |archive-date=October 27, 2016 |url-status=live}} In all cases of these adjustments along the Rio Grande under the 1905 convention, which occurred on 37 different dates from 1910 to 1976, the transferred land was small (ranging from one to 646 acres) and uninhabited.{{cite web |url=https://www.ibwc.gov/Treaties_Minutes/Minutes.html |title=IBWC Minutes |publisher=International Boundary and Water Commission |access-date=September 11, 2017}}{{cite web |url=http://www.google.com/maps/d/edit?mid=zTEHCtUumBXk.k-ueCthwuSNs |title=USA-Mexico Bancos Map |access-date=September 11, 2017}}{{cite book |title=Restless River, International Law and the Behavior of the Rio Grande |publisher=Texas Western Press |author=Mueller, Jerry E. |year=1975 |page=64 |isbn=978-0-87404-050-0}}

The Rio Grande Rectification Treaty of 1933 straightened and stabilized the river boundary through the highly developed El Paso-Juárez valley. Numerous parcels of land were transferred between the two countries during the construction period, 1935–1938. At the end, each nation had ceded an equal area of land to the other.{{cite web |title=Minutes 144 |url=http://www.ibwc.state.gov/Files/Minutes/Min144.pdf |author=International Boundary and Water Commission |access-date=June 12, 2015 |url-status=dead |archive-url=https://web.archive.org/web/20160308032837/http://www.ibwc.state.gov/Files/Minutes/Min144.pdf |archive-date=March 8, 2016}}{{cite web |title=Minutes 158 |url=http://www.ibwc.state.gov/Files/Minutes/Min158.pdf |author=International Boundary and Water Commission |access-date=June 12, 2015 |url-status=dead |archive-url=https://web.archive.org/web/20160308033025/http://www.ibwc.state.gov/Files/Minutes/Min158.pdf |archive-date=March 8, 2016}}

The Boundary Treaty of 1970 transferred an area of Mexican territory to the U.S., near Presidio and Hidalgo, Texas, to build flood control channels. In exchange, the U.S. ceded other land to Mexico, including five parcels near Presidio, the Horcon Tract and Beaver Island near Roma, Texas. On November 24, 2009, the U.S. ceded 6 islands in the Rio Grande to Mexico. At the same time, Mexico ceded 3 islands and 2 bancos to the U.S. This transfer, which had been pending for 20 years, was the first application of Article III of the 1970 Boundary Treaty.{{cite web |url=https://2009-2017.state.gov/e/oes/ocns/opa/c28187.htm |title=Maritime Boundaries |publisher=United States Department of State |access-date=August 19, 2018}}{{cite web |url=http://www.ibwc.state.gov/Treaties_Minutes/Minutes.html |title=Minutes between the United States and Mexican Sections of the IBWC |publisher=International Boundary and Water Commission |access-date=January 6, 2016 |url-status=dead |archive-url=https://web.archive.org/web/20150713015418/http://www.ibwc.state.gov/Treaties_Minutes/Minutes.html |archive-date=July 13, 2015}}{{cite web |url=http://www.ibwc.state.gov/Files/Minutes/Joint_Report_315.pdf |title=Minute 315: Adoption of the Delineation of the International Boundary on the 2008 Aerial Photographic Mosaic of the Rio Grande |publisher=International Boundary and Water Commission |date=November 24, 2009 |access-date=June 13, 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160411202233/http://www.ibwc.state.gov/Files/Minutes/Joint_Report_315.pdf |archive-date=April 11, 2016}}

On March 27, 2023, at least 38 detained migrants (mostly from Central America) were killed—and dozens more injured—in a fire started in protest inside a locked and crowded detention center cell in northern Mexico, with motives ranging from pending deportation to overcrowding and lack of access to drinking water.{{Cite web |last1=Linthicum |first1=Kate |last2=McDonnell |first2=Patrick J. |last3=Minjares |first3=Gabriela |date=March 28, 2023 |title=At least 38 migrants killed in a fire at a detention center in Mexico |url=https://www.latimes.com/world-nation/story/2023-03-28/mexico-border-dozens-dead-migrant-center-fire |access-date=March 29, 2023 |website=Los Angeles Times |language=en-US}}

{{main list|List of Mexico–United States border crossings

}}

The border separating Mexico and the U.S. is the most frequently crossed international boundary in the world,{{cite book |url=https://books.google.com/books?id=hknZxFWtWnQC&pg=PA75 |title=Retirement Without Borders: How to Retire Abroad{{snd}}in Mexico, France, Italy, Spain, Costa Rica, Panama, and Other Sunny, Foreign Places |last=Golson |first=Barry |publisher=Simon & Schuster |year=2008 |isbn=978-0-7432-9701-1 |location=New York, New York |page=75 |author2=Thia Golson |access-date=March 9, 2011}}{{cite book |url=https://books.google.com/books?id=aHYt0RNSDfgC&q=most%20frequently%20crossed%20border%20guinness&pg=PA457 |title=Guinness World Records 2009 |last=Glenday |first=Craig |publisher=Random House Digital, Inc. |year=2009 |isbn=978-0-553-59256-6 |page=457 |access-date=March 9, 2011}} with approximately 350 million legal crossings taking place annually.{{cite news |title=US, Mexico open first new border crossing in 10 years |location=Washington |url=https://www.google.com/hostednews/afp/article/ALeqM5jHLM81sN-H02Sf1CANZvBoE9mUwA |archive-url=https://web.archive.org/web/20140228012612/https://www.google.com/hostednews/afp/article/ALeqM5jHLM81sN-H02Sf1CANZvBoE9mUwA |archive-date=February 28, 2014 |newspaper=AFP |date=January 12, 2010 |access-date=December 3, 2012 |quote=The US–Mexico border is the busiest in the world, with approximately 350 million crossings per year.}}{{cite web |url=http://www.nmsu.edu/~bec/BEC/Readings/10.USMBHC-TheBorderAtAGlance.pdf |title=The United States–Mexico Border Region at a Glance |website=United States–Mexico Border Health Commission |publisher=New Mexico State University |access-date=December 3, 2012 |quote=In 2001, over 300 million two-way border crossings took place at the 43 POEs. |url-status=dead |archive-url=https://web.archive.org/web/20120915105245/http://www.nmsu.edu/~bec/BEC/Readings/10.USMBHC-TheBorderAtAGlance.pdf |archive-date=September 15, 2012}}

Border crossings take place by roads, pedestrian walkways, railroads and ferries. From west to east, below is a list of the border city "twinnings"; cross-border municipalities connected by one or more legal border crossings.

File:Bridge of the Americas (El Paso–Ciudad Juárez), June 2016.jpg

{{colbegin|colwidth=30em}}

• San Diego, California (San Ysidro) – Tijuana, Baja California (San Diego–Tijuana Metro)
• Cross Border Xpress, Otay Mesa, California – Tijuana International Airport, Baja California
• Otay Mesa, California – Tijuana, Baja California
• Tecate, California – Tecate, Baja California
• Calexico, California – Mexicali, Baja California
• Andrade, California – Los Algodones, Baja California
• San Luis, Arizona – San Luis Río Colorado, Sonora
• Lukeville, Arizona – Sonoyta, Sonora
• Sasabe, Arizona – Altar, Sonora
• Nogales, Arizona – Nogales, Sonora
• Naco, Arizona – Naco, Sonora
• Douglas, Arizona – Agua Prieta, Sonora
• Antelope Wells, New Mexico – El Berrendo, Chihuahua
• Columbus, New Mexico – Palomas, Chihuahua
• Santa Teresa, New Mexico – San Jerónimo, Chihuahua
• El Paso, Texas – Ciudad Juárez, Chihuahua (El Paso-Juarez)
• Fabens, Texas – Práxedis G. Guerrero, Chihuahua municipality
• Fort Hancock, Texas – El Porvenir, Chihuahua
• Presidio, Texas – Ojinaga, Chihuahua
• Heath Canyon, Texas – La Linda, Coahuila (closed)
• Del Rio, Texas – Ciudad Acuña, Coahuila
• Eagle Pass, Texas – Piedras Negras, Coahuila
• Laredo, Texas – Nuevo Laredo, Tamaulipas
• Laredo, Texas – Colombia, Nuevo León
• Falcon Heights, Texas – Presa Falcón, Tamaulipas
• Roma, Texas – Ciudad Miguel Alemán, Tamaulipas
• Rio Grande City, Texas – Ciudad Camargo, Tamaulipas
• Los Ebanos, Texas – Gustavo Díaz Ordaz, Tamaulipas
• Mission, Texas – Reynosa, Tamaulipas
• Hidalgo, Texas – Reynosa, Tamaulipas
• Pharr, Texas – Reynosa, Tamaulipas
• Donna, Texas – Rio Bravo, Tamaulipas
• Progreso, Texas – Nuevo Progreso, Tamaulipas
• Los Indios, Texas – Matamoros, Tamaulipas
• Brownsville, Texas – Matamoros, Tamaulipas

{{colend}}

The total population of the borderlands—defined as those counties and municipios lining the border on either side—stands at some 12 million people.

File:CBP San Diego Operations - San Ysidro (28555925151).jpg through vehicle]]

The San Ysidro Port of Entry is located between San Ysidro, California and Tijuana, Baja California. Approximately 50,000 vehicles and 25,000 pedestrians use this entry daily.{{Cite web |url=https://www.politico.com/magazine/gallery/2017/02/photo-gallery-san-ysidro-california-us-mexico-border-000710?slide=0 |title=A Day at the Busiest Border Crossing in the World |website=POLITICO Magazine |date=February 16, 2017 |language=en |access-date=July 27, 2018}} In the U.S., I-5 crosses directly to Tijuana, and the highway's southern terminus is this crossing. In 2005, more than 17 million vehicles and 50 million people entered the U.S. through San Ysidro.{{cite book |author=OECD |url=https://books.google.com/books?id=7_vRPU5LZcIC&pg=PA331 |title=Regional Development Policies in OECD Countries |year=2010 |publisher=OECD Publishing |isbn=978-92-64-08725-5 |page=331}}{{cite book |last=Berndes |first=Barry |url=https://books.google.com/books?id=h9ejDrOkkc4C&pg=PA227 |title=The San Diegan – 41st Edition |publisher=The San Diegan |year=2009 |isbn=978-1-890226-13-8 |page=227}}{{cite book |last=Gaynor |first=Tim |url=https://books.google.com/books?id=Etodgf8bEGsC&pg=PA81 |title=Midnight on the Line: The Secret Life of the U.S.–Mexico Border |date=2009 |publisher=Macmillan |isbn=978-1-4299-9462-0 |page=81}}{{cite book |author= |url=http://www.gao.gov/new.items/d08219.pdf |title=Border Security: Despite Progress, Weaknesses in Traveler Inspections Exist at Our Nation's Port of Entry |date=November 2007 |publisher=United States Government Accountability Office |page=10 |id=GAO-08-219 |quote=and the busiest land crossing in the United States at San Ysidro, California, which processes over 17 million vehicles a year (see fig. 1); |access-date=September 8, 2014}} Among those who enter the U.S. through San Ysidro are transfronterizos, American citizens who live in Mexico and attend school in the U.S.{{cite news |last=Brown |first=Patricia Leigh |date=January 16, 2012 |title=Young U.S. Citizens in Mexico Brave Risks for American Schools |newspaper=New York Times |url=https://www.nytimes.com/2012/01/17/us/young-us-citizens-in-mexico-up-early-to-learn-in-the-us.html?pagewanted=all&_r=0 |access-date=September 8, 2014}}

It has influenced the every day lifestyle of people that live in these border towns.{{Cite news |url=https://www.nytimes.com/interactive/2017/02/08/world/americas/before-the-wall-life-along-the-us-mexico-border.html |title=Before the Wall: Life Along the U.S.-Mexico Border |last=Ahmed |first=Azam |newspaper=The New York Times |date=February 8, 2017 |access-date=July 27, 2018 |language=en}} Along the coast of Baja California, there are neighborhoods of Americans living in Tijuana, Rosarito Beach, and Ensenada, whose residents commute to the U.S. daily to work.{{cite book |last1=Yogerst |first1=Joe |url=https://books.google.com/books?id=fk3uzf9zSwAC&pg=PA341 |title=Traveler's Companion California |last2=Mellin |first2=Maribeth |date=2002 |publisher=Globe Pequot |isbn=978-0-7627-2203-7 |page=341 |access-date=September 8, 2014}} Additionally, many Mexicans also enter the U.S. to commute daily to work.{{cite book |last=Levine |first=Robert N. |url=https://books.google.com/books?id=IXq7CdAiQOQC&pg=PA190 |title=A Geography Of Time: On Tempo, Culture, And The Pace Of Life |date=2008 |publisher=Basic Books |isbn=978-0-7867-2253-2 |page=190 |access-date=September 8, 2014}} In 1999, 7.6% of the labor force of Tijuana was employed in San Diego.{{cite book |last1=Mendoza |first1=Cristobal |title=Transboundary Policy Challenges in the Pacific Border Regions of North America |last2=Loucky |first2=James |date=2008 |publisher=University of Calgary Press |isbn=978-1-55238-223-3 |editor-last1=Alper |editor-first=Donald K. |page=55 |chapter=Recent Trends in Mexico-U.S. Border Demographics |editor-last2=Day |editor-first2=John Chadwick |editor-last3=Loucky |editor-first3=James |chapter-url=https://books.google.com/books?id=KDc2r0SC5PIC&pg=PA55}}

File:San Diego San Ysidro 01.jpg

The average wait time to cross into the U.S. is approximately an hour. The thousands of vehicles that transit through the border every day is causing air pollution in San Ysidro and Tijuana.{{Cite news |url=https://www.voiceofsandiego.org/topics/science-environment/san-ysidro-is-getting-a-clearer-look-at-just-how-polluted-it-is/ |title=San Ysidro Is Getting a Clearer Look at Just How Polluted it is |date=April 23, 2018 |work=Voice of San Diego |access-date=July 27, 2018 |language=en-US}} The emission of carbon monoxide (CO) and other vehicle related air contaminants have been linked to health complications such as cardiovascular disease, lung cancer, birth outcomes, premature death, obesity, asthma and other respiratory diseases.{{Cite web |url=https://www.sandag.org/uploads/publicationid/publicationid_1933_18945.pdf |title=Border Health Equity Transportation Study |date=February 27, 2015}} The high levels of traffic collusion and the extended wait times has affected the mental health, stress levels, and aggressive behavior of the people who cross frequently.

The San Ysidro border is heavily policed, separated by three walls, border patrol agents and the U.S. Immigration and Customs Enforcement.{{Cite web |url=https://foreignpolicy.com/2011/06/24/the-worlds-most-dangerous-borders/ |title=The World's Most Dangerous Borders |website=Foreign Policy |date=June 24, 2011 |language=en |access-date=July 27, 2018}}

Tijuana is the next target for San Diegan developers because of its fast-growing economy, lower cost of living, cheap prices and proximity to San Diego.{{Cite web |url=https://www.expatistan.com/cost-of-living/tijuana |title=Cost of Living in Tijuana, Mexico. Jul 2018 prices in Tijuana. |website=Expatistan, cost of living comparisons |language=en |access-date=July 27, 2018}} While this would benefit the tourist aspect of the city, it is damaging to low-income residents that will no longer be able to afford the cost of living in Tijuana.{{Cite news |url=https://www.buzzfeednews.com/article/karlazabludovsky/tijuana-wants-you-to-forget-everything-you-know-about-it |title=Tijuana Wants You To Forget Everything You Know About It |work=BuzzFeed News |access-date=July 27, 2018 |language=en}} Tijuana is home to many deportees from the U.S., many who have lost everything and do not have an income to rely on and are now in a new city in which they have to quickly adapt in order to survive.{{cite news |title=This is what the hours after being deported look like |url=https://www.theguardian.com/inequality/2017/dec/12/mexico-deportation-tijuana-trump-border |date=2017-12-12 |work=The Guardian |last1=Lakhani |first1=Nina |access-date=July 27, 2018 |language=en-GB |issn=0261-3077}} San Diego developers would bring many benefits to Tijuana, but deportees and the poor run the risk of being impacted by the gentrification of Tijuana.{{Cite news |url=https://www.voiceofsandiego.org/border/small-san-diego-developers-see-a-new-frontier-in-tijuana/ |title=San Diego Developers See a New Frontier in Tijuana |date=November 30, 2015 |work=Voice of San Diego |access-date=July 27, 2018 |language=en-US}}

{{main|Western Hemisphere Travel Initiative}}

Image:SanYsidroBorderCrossing.JPG]]

In late 2006, the U.S. Department of Homeland Security (DHS) announced a rule regarding new identification requirements for U.S. citizens and international travelers entering the U.S. implemented on January 23, 2007. This final rule and first phase of the WHTI specifies nine forms of identification, one of which is required to enter the U.S. by air: a valid passport; a passport card; a state enhanced driver's license or state enhanced non-driver ID card (available in Michigan, New York, Vermont, and Washington{{cite web |url=http://www.getyouhome.gov/html/lang_eng/eng_edl.html |title=WHTI: Enhanced Drivers License |website=Getyouhome.gov |archive-url=https://web.archive.org/web/20120215123453/http://www.getyouhome.gov/html/lang_eng/eng_edl.html |archive-date=February 15, 2012 |url-status=dead |access-date=April 9, 2018}}) approved by the Secretary of Homeland Security; a trusted traveler program card (Global Entry, NEXUS, FAST, or SENTRI); an enhanced tribal identification card; a Native American Tribal Photo Identification Card;

Form I-872 – American Indian Card; a valid Merchant Mariner Document when traveling in conjunction with official maritime business; or a valid U.S. military identification card when traveling on official orders.{{Citation |title=DHS Announces Final Western Hemisphere Air Travel |date=December 5, 2006 |url=http://www.acte.org/resources/view_article.php?id=105 |archive-url=https://web.archive.org/web/20071216073223/http://www.acte.org/resources/view_article.php?id=105 |url-status=dead |publisher=Association of Cotpotrate Travel Executives |access-date=December 2, 2007 |archive-date=December 16, 2007}}{{Citation |title=Western Hemisphere Travel Initiative: The Basics |url=https://www.dhs.gov/xtrvlsec/crossingborders/whtibasics.shtm |archive-url=https://web.archive.org/web/20071226044426/https://www.dhs.gov/xtrvlsec/crossingborders/whtibasics.shtm |url-status=dead |publisher=U.S. Department of Homeland Security |access-date=December 2, 2007 |archive-date=December 26, 2007}}{{Citation |title=Western Hemisphere Travel Initiative |date=January 13, 2008 |url=https://travel.state.gov/travel/cbpmc/cbpmc_2223.html |archive-url=https://web.archive.org/web/20070125092329/http://travel.state.gov/travel/cbpmc/cbpmc_2223.html |url-status=dead |publisher=U.S. Department of State, Bureau of Consular Affairs |access-date=January 12, 2007 |archive-date=January 25, 2007}}{{cite web |url=http://www.nmborder.com/travel_usa.html |title=Traveling to USA? |archive-url=https://web.archive.org/web/20040911062821/http://www.nmborder.com/travel_usa.html |archive-date=September 11, 2004 |url-status=dead}}

In August 2015, Mexico began enforcing a rule that all foreign citizens that plan to stay in the country for more than seven days or are travelling on business will have to pay a 330 pesos ($21) fee and show their passport.{{cite web |url=http://www.sandiegouniontribune.com/news/border-baja-california/sdut-mexico-opens-new-pedestrian-port-san-ysidro-2015aug19-story.html |title=New pedestrian crossing unveiled in Tijuana |last=Dibble |first=Sandra |website=Sandiegouniontribune.com |access-date=April 9, 2018 |date=August 20, 2015}}{{cite news |url=http://www.csmonitor.com/USA/USA-Update/2015/0820/Why-it-s-Mexico-s-turn-to-tighten-the-US-border |title=Why it's Mexico's turn to tighten the US border |date=August 20, 2015 |newspaper=Christian Science Monitor |access-date=April 9, 2018}}{{cite news |url=https://www.npr.org/sections/thetwo-way/2015/08/20/433155278/new-rules-go-into-effect-at-busy-u-s-mexico-border-crossing |title=New Rules Go Into Effect At Busy U.S.–Mexico Border Crossing |website=Npr.org |date=August 20, 2015 |access-date=April 9, 2018 |last1=Wagner |first1=Laura}}

File:Mexico Baja California passport stamp.jpg land border crossing]]

When animals are imported from one country to another, there is the possibility that diseases and parasites can move with them. Thus, most countries impose animal health regulations on the import of animals. Most animals imported to the U.S. must be accompanied by import permits obtained in advance from the U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) and/or health certification papers from the country of origin.

Veterinary inspections are often required, and are available only at designated ports;{{cite web |url=http://www.aphis.usda.gov/vs/ncie/portlist.html |title=Ports Designated for the Importation of Animals |publisher=Animal and Plant Health Inspection Service (APHIS) |archive-url=https://web.archive.org/web/20070202135654/http://www.aphis.usda.gov/vs/ncie/portlist.html |archive-date=February 2, 2007 |access-date=October 5, 2011}}

advance contact with port veterinarians is recommended.{{cite web |url=http://www.aphis.usda.gov/vs/ncie/portvet.html |title=Port Veterinarian List |publisher=Animal and Plant Health Inspection Service (APHIS) |archive-url=https://web.archive.org/web/20061209004821/http://www.aphis.usda.gov/vs/ncie/portvet.html |archive-date=December 9, 2006 |access-date=October 5, 2011}} Animals crossing the U.S.–Mexico border may have a country of origin other than the country where they present for inspection. Such animals include those from the U.S. that cross to Mexico and return, and animals from other countries that travel overland through Mexico or the U.S. before crossing the border.

File:Tijuana Border Traffic.jpg

APHIS imposes precautions to keep out several equine diseases, including glanders, dourine, equine infectious anemia, equine piroplasmosis, Venezuelan equine encephalitis, and contagious equine metritis.{{cite web |url=http://permanent.access.gpo.gov/lps3025/imphorse.html |title=Equine Importation |publisher=Animal and Plant Health Inspection Service (APHIS) |archive-url=https://web.archive.org/web/20101017004412/http://www.aphis.usda.gov/import_export/animals/animal_import/equine/equine_import_quarantine.shtml |archive-date=October 17, 2010 |access-date=October 5, 2011}} APHIS also checks horses to prevent the introduction of ticks and other parasites. In the Lower Rio Grande Valley, U.S. Department of Agriculture inspectors look for horses and livestock that stray across the border carrying ticks. These animals are often called wetstock, and the inspectors are referred to as tickriders.{{cite book |last=Miller |first=Tom |title=On the Border: Portraits of America's Southwestern Frontier |publisher=iUniverse |year=2000 |isbn=978-0-8165-0943-0 |pages=72–73}}

Per APHIS, horses originating from Canada can enter the U.S. with a Canadian government veterinary health certificate and a negative test for EIA. Horses from Mexico must have a health certificate; pass negative tests for EIA, dourine, glanders, and EP at a USDA import center; and undergo precautionary treatments for external parasites at the port of entry. Horses from other Western Hemisphere countries must have the same tests as those from Mexico and, except for horses from Argentina, must be held in quarantine for at least seven days as a check for VEE.

APHIS imposes similar testing and certification requirements on horses from other parts of the world but without the quarantine for VEE. These horses are held in quarantine—usually three days—or until tests are completed. Because the disease equine piroplasmosis (equine babesiosis) is endemic in Mexico but not established in the U.S.,{{cite web |url=http://www.ca.uky.edu/gluck/q/2003/oct03/q_main.htm |title=Veterinary Science |website=Ca.uky.edu |access-date=April 9, 2018}} transportation of horses from Mexico to the U.S. requires evaluation of horses for the presence of this disease. A leading exception to this rule is the special waiver obtained by riders participating in the Cabalgata Binacional Villista (see cavalcade).

Import from the U.S. to Mexico requires evidence within the prior 45 days of freedom from EIA, among other requirements.{{cite web |url=http://www.aphis.usda.gov/NCIE/iregs/animals/mx_eq_040406.pdf |title=Import health requirements of Mexico for horses (non slaughter) exported from the United States |date=December 2005 |publisher=Animal and Plant Health Inspection Service (APHIS) |archive-url=https://web.archive.org/web/20090419233214/http://www.aphis.usda.gov/regulations/vs/iregs/animals/downloads/mx_eq.pdf |archive-date=April 19, 2009 |access-date=October 5, 2011}}

File:Canyon, Rio Grande, Texas.jpeg is located at the border.]]

Data from the U.S. Border Patrol Agency's 2010 annual report shows that among the total number of border crossings without documentation from various countries into the U.S., 90% were from Mexico alone. In addition, there are more than 6 million undocumented Mexican nationals residing in the U.S.{{Cite book |url=https://www.nap.edu/read/13498/chapter/1#ii |title=Options for Estimating Illegal Entries at the U.S.–Mexico Border The National Academies Press |publisher=The National Academies Press |year=2013 |isbn=978-0-309-26426-6 |location=Washington D.C. |language=en |doi=10.17226/13498}} The border has a very high rate of documented and undocumented migrant crossings every year. With such a high rate of people crossing annually to the U.S., the country has invested in several distinct security measures.

In 2010, President Barack Obama signed an appropriation bill which gave the Customs and Border Protection, specifically the Border Patrol, 600 million dollars to implement and improve security. The U.S. government has invested many millions of dollars on border security, although this has not stopped undocumented immigration in the U.S.{{cite journal |last1=Martínez |first1=Ruben |title=Fortress America |journal=Index on Censorship |date=2004 |volume=33 |issue=3 |pages=48–52 |doi=10.1080/03064220408537373 |s2cid=220990170}} In June 2018, the U.S. government announced installation of facial recognition system for monitoring immigrant activities.{{cite web |title=US government to use facial recognition technology at Mexico border crossing |url=https://www.theguardian.com/technology/2018/jun/05/facial-recognition-us-mexico-border-crossing |website=The Guardian |date=2018-06-05 |last1=Levin |first1=Sam |language=en |access-date=June 6, 2018}}

{{See also|Illegal immigration to the United States|Operation Lone Star}}

File:South Texas, Border Patrol Agents, McAllen Horse Patrol Unit.jpg agents in southern Texas in 2013]]

The Border Patrol was created in 1924 with its primary mission to detect and prevent the illegal entry of immigrants into the U.S. Together with other law enforcement officers, the Border Patrol maintains the U.S.' borderlands—regulating the flow of legal immigration and goods while patrolling for undocumented migrants and trafficking of people and contraband. The present strategy to enforce migration along the U.S.–Mexico border is by the means of "prevention through deterrence". Its primary goal is to completely prevent undocumented immigrants from entering the U.S. from Mexico rather than apprehending the unauthorized who are already in the country. As assertive as it was, "prevention through deterrence" was arguably unsuccessful, with a doubling in size of undocumented immigrants population during the two decades leading up to 2014.{{Cite journal |last=Ewing |first=Walter A. |date=2014 |title=Enemy Territory: Immigration Enforcement in the US–Mexico Borderlands |url=https://heinonline.org/HOL/P?h=hein.journals/jmighs2&i=198. |journal=Journal on Migration and Human Security |volume=2 |issue=3 |pages=198–222 |via=HeinOnline |doi=10.14240/jmhs.v2i3.32 |doi-broken-date=November 1, 2024 |doi-access=free}}

In order to effectively enforce border protection, the U.S.' policies and regulations have looked to make border crossings more hazardous through the implementation of various operations, one of those being the "funnel effect". The tactic was meant to discourage migration from Mexico into the U.S. by forcing migrants to travel further around barriers where the terrain and weather are more risky, but the strategy was not as successful as initially planned.{{Cite journal |last=Newell |first=Bryce Clayton |date=May 2016 |title=Information seeking, technology use, and vulnerability among migrants at the United States–Mexico border |journal=Information Society |volume=32 |issue=3 |pages=176–191 |doi=10.1080/01972243.2016.1153013 |doi-access=free}} As a result, the effect funneled more immigrants to their death even with the assistance of coyotes (smugglers). Not only has this approach caused fatalities throughout the U.S.–Mexico border, but it has even stirred up a nuisance for documented immigrants and American citizens. There has been general concern about the Border Patrol and other agencies abusing their authority by racial profiling and conducting unwarranted searches outside the exception of the {{convert|25|mi|abbr=on|order=flip}} border zone, but still within the {{convert|100.|mi|abbr=on|order=flip}} border zone.

In 2012, Border Patrol agents made over 364,000 arrests of people illegally entering the country. Considerable success has been achieved in restoring integrity and safety to the border, by putting in place a border-control strategy. These include Operation Gatekeeper in San Diego; Operation Hold the Line in El Paso; Operation Rio Grande in McAllen; Operation Safeguard in Tucson; and the Arizona Border Control Initiative along the Arizona border.{{cite web |url=https://www.cbp.gov/border-security/along-us-borders/overview |title=Border Patrol Overview |website=cbp.gov}} {{PD-notice}}

According to Vulliamy, one in five Mexican nationals will visit or work in the U.S. at one point in their lifetime.{{cite book |last=Vulliamy |first=Ed |url=https://archive.org/details/amexicawaralongb00vull |title=Amexica: War Along the Borderline |date=2010 |publisher=Farrar, Straus and Giroux |isbn=978-0-374-10441-2}} As of 2010, the border is guarded by more than 20,000 Border Patrol agents, more than at any time in its history.{{cite web |last=U.S. Department of Homeland Security |title=Fact Sheet: Southwest Border Next Steps |date=June 23, 2010 |url=https://www.dhs.gov/ynews/releases/pr_1277310093825.shtm |access-date=August 6, 2010}} The border is paralleled by U.S. Border Patrol interior checkpoints on major roads generally between {{convert|25|and|75|mi|abbr=on|order=flip|km}} from the U.S. side of the border, and garitas generally within {{Convert|50.|km|abbr=on}} of the border on the Mexican side.{{cite web |url=http://www.gao.gov/new.items/d05435.pdf |title=Border Patrol: Available Data on Interior Checkpoints Suggest Differences in Sector Performance |publisher=United States General Accounting Office |date=July 2005}}{{cite web |url=http://www.gao.gov/new.items/d09824.pdf |title=Border Patrol: Checkpoints Contribute to Border Patrol's Mission, but More Consistent Data Collection and Performance Measurement Could Improve Effectiveness |publisher=United States General Accounting Office |date=August 2009}}{{cite web |url=http://www.aduanas.sat.gob.mx/aduana_mexico/2007/RCGMCE/2007/Anexo_25.doc |author=Aduana Mexico |year=2007 |title=Aduanas 25 de las Reglas de Caracter General en Materia de Comercio Exterior para 2007 |language=es |archive-url=https://web.archive.org/web/20120224013954/http://www.aduanas.sat.gob.mx/aduana_mexico/2007/RCGMCE/2007/Anexo_25.doc |archive-date=February 24, 2012}}

File:Sinaloa Cartel Drug Tunnel.jpg tunnel under the U.S.–Mexico border used by the Sinaloa Cartel]]

There are an estimated half a million illegal entries into the U.S. each year.{{cite web |url=http://www.gao.gov/new.items/d06770.pdf |publisher=Government Accountability Office |title=Illegal Immigration – Border-Crossing Deaths Have Doubled Since 1995; Border Patrol's Efforts to Prevent Deaths Have Not Been Fully Evaluated |page=42 |date=August 2006}} Border Patrol activity is concentrated around border cities such as San Diego and El Paso which have extensive border fencing. This means that the flow of illegal immigrants is diverted into rural mountainous and desert areas, leading to several hundred migrant deaths along the Mexico–U.S. border of those attempting to cross into the U.S. from Mexico illegally and vice versa.

Undocumented labor contributes $395 billion to the economy every year. While the U.S. is in favor of immigration, the increase in undocumented immigration has given border-crossing a negative image. There are around 11.5 million undocumented workers in the U.S. today, and 87% of undocumented immigrants have been living in the U.S. for more than 7 years.{{cite web |url=http://www.pulsamerica.co.uk/2013/07/the-u-s-mexico-border-under-the-economic-lens-and-in-the-historical-frame/ |title=The U.S.–Mexico border: under the economic lens and in the historical frame |website=pulsamerica.co.uk |access-date=November 19, 2017 |archive-url=https://web.archive.org/web/20181006011832/http://www.pulsamerica.co.uk/2013/07/the-u-s-mexico-border-under-the-economic-lens-and-in-the-historical-frame/ |archive-date=October 6, 2018 |url-status=dead}} Local economies that develop on the Mexican side capitalize not only on available skills but also on available, usually discarded, materials. Small businesses trade in clothes that are purchased by the pound and cardboard from the U.S. Some items, like the used tires found everywhere along the border, are made into certain items that support local economies and define a border.{{cite web |url=http://www.smithsonianeducation.org/migrations/bord/intro.html |title=Borders and Identity |website=smithsonianeducation.org}}

The Secure Fence Act of 2006 was passed providing for the construction of {{convert|700.|mi|km|abbr=on|order=flip}} of high-security fencing. Attempts to complete the construction of the Mexico–United States barrier have been challenged by the Mexican government and various U.S.–based organizations.

In January 2013, the Government Accountability Office released a report stating that the U.S. Border Patrol intercepted 61% of individuals illegally crossing the border in 2011, which translates to 208,813 individuals not apprehended.{{cite news |first=Stephen |last=Dinan |title=Interceptions of immigrants stubbornly low |url=http://m.washingtontimes.com/news/2013/jan/9/interceptions-immigrants-stubbornly-low/ |newspaper=Washington Times |date=January 9, 2013 |access-date=January 12, 2013}} 85,827 of the 208,813 would go on to illegally enter the U.S., while the rest returned to Mexico and other Central American countries. The report also shows that the number of illegal border crossings has dropped.

{{Graph:Chart|width=900|height=200|type=rect|xAxisTitle=Fiscal Year (Years shown here: 1990–2017.|yAxisTitle=Apprehensions (in thousands)

|x=1990,1991,1992,1993,1994,1995,1996,1997,1998,1999,2000, 2001,2002,2003,2004,2005,2006,2007,2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2019,2020,2021

|y= 1049.321, 1077.876, 1145.574, 1212.886, 979.101, 1271.390, 1507.020, 1368.707, 1516.680, 1537.000, 1643.679, 1235.718, 929.809, 905.065, 1139.282, 1171.396, 1071.972, 858.638, 705.005, 540.865, 447.731, 327.577, 356.873, 414.397, 479.371, 331.333, 408.870, 303.916, 977.509, 458.088, 1734.686

|showValues=offset:4}}

The apprehensions per (fiscal) year are shown in the graph; they reached a maximum of over 1.643 million in the year 2000.{{Cite web |url=https://www.cbp.gov/sites/default/files/assets/documents/2017-Dec/BP%20Southwest%20Border%20Sector%20Apps%20FY1960%20-%20FY2017.pdf |title=United States Border Patrol |access-date=June 27, 2018 |archive-date=June 24, 2018 |archive-url=https://web.archive.org/web/20180624063409/https://www.cbp.gov/sites/default/files/assets/documents/2017-Dec/BP%20Southwest%20Border%20Sector%20Apps%20FY1960%20-%20FY2017.pdf |url-status=dead}} Similar numbers had been reached in 1986 with over 1.615 million.

The increase of border security throughout the years has progressively made crossings at the U.S.–Mexico border more dangerous, which has developed a human rights crisis at the border. The number of migrant deaths occurring along the U.S.–Mexico border has dramatically increased since the implementation of the funnel effect.{{Cite journal |last=Johnson |first=Leif |date=November 2015 |title=Material Interventions on the US-Mexico Border: Investigating a Sited Politics of Migrant Solidarity |journal=Antipode |volume=47 |issue=5 |pages=1244 |doi=10.1111/anti.12151}} Along the Arizona-Mexico border, only seven migrant deaths were recorded in 1996; however, the remains of over 2,000 migrants were discovered from 2001 to 2012. Since the majority of deaths occur in rural areas, where extreme temperatures are common, it is likely the number of recorded deaths are far below the total. Because of the harsh, inaccessible terrain, human remains may not be found for years or ever.{{Cite SSRN |last=Martinez |first=Daniel E. |last2=Reineke |first2=Robin |last3=Rubio-Goldsmith |first3=Raquel |last4=Anderson |first4=Bruce E. |last5=Hess |first5=Gregory L. |last6=Parks |first6=Bruce O. |date=2013 |title=A Continued Humanitarian Crisis at the Border: Undocumented Border Crosser Deaths Recorded by the Pima County Office of the Medical Examiner, 1990–2012 |ssrn=2633209}}

The Human Rights Watch cited on April 22, 2020, that a U.S.–Mexico border shutdown could be expected following the COVID-19 public health emergency. According to HRW, the new rule introduced by the CDC overlooks the fact that the U.S. is obligated to protect refugees from return to conditions threatening prosecution, as per treaties.{{cite web |url=https://www.hrw.org/news/2020/04/22/tell-trump-administration-protect-asylum-seekers |title=Tell the Trump Administration to Protect Asylum Seekers |access-date=April 22, 2020 |website=Human Rights Watch |date=April 22, 2020}}

President Joe Biden's border executive plan as the COVID-19 restrictions – known as Title 42 – expired in May 2023.

Under Title 42, which had been in effect since March 2020, many border crossers have been quickly deported to Mexico without a chance for asylum.{{cite news |last1=Blake |first1=Michael |title=Border crossings top 10,000 daily as migrants seek US entry before Title 42 ends |url=https://www.reuters.com/world/us/biden-restricts-asylum-access-mexico-border-title-42-ends-2023-05-10/ |work=Reuters |date=2023}}

In February 2025, migrant arrests at the Mexico-United States border were projected to reach a record low, with U.S. Border Patrol expecting around 8,500 apprehensions, according to the Department of Homeland Security. This decline followed President Donald Trump’s return to office on January 20, when he implemented strict immigration policies, including an asylum ban and increased military presence at the border. The American Civil Liberties Union challenged the ban in court. The previous record low was in April 2017, early in Trump’s first term. Arrests had previously dipped at the start of his 2017-2021 presidency before rising again in later years.{{Cite web |last=Hesson |first=Ted |last2=Cooke |first2=Kristina |date=28 February 2025 |editor-last=Maler |editor-first=Sandra |title=Migrant arrests at US-Mexico border near record low in February |url=https://www.reuters.com/world/americas/migrant-arrests-us-mexico-border-approach-record-low-february-2025-02-27/ |access-date=4 March 2025 |website=Reuters}}

{{main|Mexico–United States barrier}}

The U.S. government had plans in 2006, during the Bush administration, to erect a border fence along the Mexico–U.S. border. The controversial proposal included creating many individual fences. Almost {{Convert|600.|mi|km|abbr=on|order=flip}} of fence were constructed, with each of the individual fences composed of steel and concrete. In between these fences are infrared cameras and sensors, National Guard soldiers, and SWAT teams on alert, giving rise to the term "virtual fence". Construction on the fence began in 2006, with each mile costing the U.S. government about $2.8 million.{{cite journal |last=Hodge |first=Roger D. |title=Borderworld: How the U.S. Is Reengineering Homeland Security |url=http://www.popsci.com/technology/article/2011-12/how-us-reengineering-homeland-security-borders |journal=Popular Science |volume=280 |issue=1 |year=2012 |pages=56–81}} In 2010, the initiative was terminated because of costs, after having completed {{convert|640.|mi|km|abbr=on|order=flip}} of either barrier fence or vehicle barriers, that were either new or had been rebuilt over older, inferior fencing. The Boeing-built SBI-net systems of using radar, watchtowers, and sensors (without a fence or physical barrier) were scrapped for being over budget, full of glitches, and far behind schedule.{{cite news |url=https://www.washingtonpost.com/wp-dyn/content/article/2010/03/16/AR2010031603573.html |title=Work to cease on 'virtual fence' along U.S.–Mexico border |last=Hsu |first=Spencer S. |date=March 16, 2010 |newspaper=The Washington Post}}

File:US-Mexico border fence.jpg|The U.S.–Mexico border fence near El Paso, Texas

File:BorderAtJacumba.jpg|Portion of border near Jacumba, California, in 2003

File:BorderAtJacumba2.jpg|Portion of border near Jacumba, California, in 2009 with enhanced security

File:Pedestrian border crossing sign Tijuana Mexico.jpg

According to the U.S. Border Patrol, apprehensions of Central Americans at the border reduced from 70,000 to 55,000 attempted illegal migrants from 2007 to 2011. Thereafter, the number of apprehensions increased dramatically to 95,000 in 2012, 150,000 in 2013 and 220,000 in 2014. The increased apprehensions could have been the result of improved border security or a dramatic rise in attempted crossings, or both.{{cite web |title=Statistics – SW Border apprehensions |url=https://www.cbp.gov/newsroom/stats/usbp-sw-border-apprehensions |website=www.cbp.gov |publisher=CBP – US Border patrol (Official website) |access-date=November 6, 2018}}

In the fiscal year of 2006, there were 29 confirmed border incursions by Mexican government officials, of which 17 were by armed individuals. Since 1996, there have been 253 incursions by Mexican government officials.{{cite news |url=http://www.signonsandiego.com/news/mexico/20080109-1533-mexico-us-borderincursions.html |title=Report: Border Patrol confirms 29 incursions by Mexican officials into U.S. in 2007 |newspaper=San Diego Union Tribune |access-date=January 17, 2008}}{{cite web |url=https://www.youtube.com/watch?v=pEKUJGT2xr4 |archive-url=https://ghostarchive.org/varchive/youtube/20211221/pEKUJGT2xr4 |archive-date=December 21, 2021 |url-status=live |title=MSNBC report on Border incursion Oct 18 2007 |date=October 18, 2007 |publisher=MSNBC |access-date=January 17, 2008}}{{cbignore}}{{cite web |url=http://www.msnbc.msn.com/id/11226144 |archive-url=https://web.archive.org/web/20060318115739/http://www.msnbc.msn.com/id/11226144/ |url-status=dead |archive-date=March 18, 2006 |title=Mexican incursions inflame border situation |publisher=MSNBC |access-date=January 17, 2008}} In 2014 the U.S. Department of Homeland Security informed California Representative Duncan D. Hunter that since 2004, there have been 300 documented border incursions, which resulted in 131 individuals being detained.{{cite web |url=http://hunter.house.gov/press-release/dhs-hunter-more-300-border-incursions-mexican-military-and-law-enforcement-authoriti-0 |title=DHS to Hunter: More than 300 border incursions by Mexican military and law enforcement authorities since January 2004 |date=June 17, 2014 |website=Congressman Duncan Hunter |publisher=United States House of Representatives |access-date=June 17, 2014 |archive-date=July 13, 2019 |archive-url=https://web.archive.org/web/20190713105000/https://hunter.house.gov/press-release/dhs-hunter-more-300-border-incursions-mexican-military-and-law-enforcement-authoriti-0 |url-status=dead}}

On August 3, 2008, Mexican military personnel crossed into Arizona from Mexico and encountered a U.S. Border Patrol agent, whom they held at gunpoint. The soldiers later returned to Mexico, as backup Border Patrol agents came to investigate.{{cite news |url=http://washingtontimes.com/news/2008/aug/06/soldiers-cross-into-us-hold-guns-to-agent/ |title=Border patrol agent held at gunpoint |work=Washington Times |date=August 8, 2008}}

Proponents of greater spending on the border argue that continuing the buildup is necessary because of increased violence and drug trafficking from Mexico spilling into the U.S.{{cite web |last=Potter |first=Mark |title=Debate rages over Mexico 'spillover violence' in U.S |date=March 15, 2012 |url=http://dailynightly.nbcnews.com/_news/2012/03/15/10701978-debate-rages-over-mexico-spillover-violence-in-us?lite |publisher=NBC News |access-date=September 24, 2012}} However, critics such as the Washington Office on Latin America have argued that the diminishing number of border crossings can only be partially attributed to U.S. security measures. Unintentional factors, such as a weakened U.S. economy in the wake of the 2008 financial crisis and the Mexican drug war have made attempting illegal border crossings more risky and less rewarding.{{cite web |url=http://www.insightcrime.org/news-analysis/further-buildup-on-us-mexico-border-unnecessary-report |title=Further Buildup on US–Mexico Border Unnecessary: Report |newspaper=InSight Crime |date=April 20, 2012 |access-date=December 7, 2014}}

In 2019, there have been humanitarian crises on the border because of lack of resources. Migrant children have specifically been affected.Stenn, L. (June 25, 2019). Hundreds of Migrant Children Moved From Border Facility After Poor Conditions Exposed. Retrieved from https://roguerocket.com/2019/06/25/hundreds-of-migrant-children-moved-from-border-facility-after-poor-conditions-exposed/ Democratic members of the House of Representatives introduced legislation that would aid the humanitarian crisis by giving $4.5 billion to emergency spending to address the humanitarian crisis at the border, with significant funding for priorities including legal assistance, food, water, and medical services, support services for unaccompanied children, alternatives to detention, and refugee services.House Democrats Introduce Emergency Border Supplemental. (June 21, 2019). Retrieved from https://appropriations.house.gov/news/press-releases/house-democrats-introduce-emergency-border-supplemental

Distribution of natural resources across the border has also been a major challenge, particularly for water use and water quality. Toxic sewage flowing into Mexico, and over-consumption of water from the Colorado River Basin and middle-lower Rio Grande have been central to the conflict. Large-scale infrastructure investments may be necessary to address the growing water and energy issues in this arid region.{{cite journal |title=Combatting water scarcity and economic distress along the US-Mexico border using renewable powered desalination |journal=Applied Energy |volume=291 |date=June 1, 2021 |issn=0306-2619 |doi=10.1016/j.apenergy.2021.116765 |url=https://www.sciencedirect.com/science/article/pii/S0306261921002725 |access-date=July 2, 2021 |page=116765 |last1=Roggenburg |first1=Michael |last2=Warsinger |first2=David M. |last3=Bocanegra Evans |first3=Humberto |last4=Castillo |first4=Luciano |s2cid=233583448}}

File:2019 US Meixco Border Crossing apprehension (48036606282).jpg

In 2016, Republican nominee for president Donald Trump proposed building a border wall to control immigration. He declared that, as president, he would force Mexico to "pay for it."{{cite web |title=Mexican president disputes Trump over border wall payment discussion |url=http://www.cnn.com/2016/08/30/politics/donald-trump-enrique-pea-nieto-mexico/ |website=CNN |date=2016-09-01 |last1=Collinson |first1=Stephen |last2=Diamond |first2=Jeremy |access-date=October 7, 2016}}{{cite web |title=How realistic is Donald Trump's Mexico wall? |url=https://www.bbc.com/news/world-us-canada-37243269 |website=BBC News |date=2016-09-01 |language=en-GB |access-date=October 7, 2016}} On January 25, 2017, several days after his inauguration and two days in advance of a planned meeting in Washington, D.C., with Mexican President Enrique Peña Nieto, new U.S. president Trump signed Executive Order 13767 to enable the building of the wall.{{cite web |title=Trump orders wall to be built on Mexico border |url=https://www.bbc.co.uk/news/world-us-canada-38740717 |website=BBC News |date=2017-01-26 |language=en-GB |access-date=January 26, 2017}} Peña Nieto denied that Mexico would pay for the wall and declined the meeting.{{cite web |title=Mexico: We will not pay for Trump border wall |url=https://www.bbc.co.uk/news/world-us-canada-38753826 |website=BBC News |date=2017-01-26 |language=en-GB |access-date=January 26, 2017}} Shortly after, Trump announced that he intended to impose a 20% tariff on Mexican goods.{{Cite web |url=https://www.reuters.com/article/us-usa-trump-mexico-idUSKBN15A1VF |title=Trump seeks 20 percent tax on Mexico goods to pay for wall, crisis deepens |date=January 26, 2017 |website=Reuters |language=en-GB |access-date=January 26, 2017}} Mexico did not make any payments.{{cite web |last1=Baum |first1=Caroline |title=Forget what Donald Trump said: Tariffs are a tax on American consumers |url=https://www.marketwatch.com/story/forget-what-donald-trump-said-tariffs-are-a-tax-on-american-consumers-2019-03-06 |access-date=March 7, 2019 |website=MarketWatch |date=March 6, 2019}}

On September 20, 2017, California Attorney General Xavier Becerra filed a lawsuit alleging that the Trump administration has overstepped its powers in expediting construction of a border wall.{{cite news |first1=Patrick |last1=McGreevy |first2=Jazmine |last2=Ulloa |website=Los Angeles Times |url=https://www.latimes.com/politics/la-pol-ca-xavier-becerra-trump-wall-lawsuit-20170920-story.html |title=California again steps up to Trump, this time to stop the border wall |date=September 20, 2017 |url-access=limited}}State of California Department of Justice, September 20, 2017: [https://oag.ca.gov/news/press-releases/attorney-general-becerra-constitution-rule-law-barriers-trump-border-wall Attorney General Becerra: Constitution, Rule of Law Barriers to Trump Border Wall] (Press Release) As of the end of 2017, Mexico had not agreed to pay any amount toward the wall, no new tariffs on Mexican goods had been considered by the U.S. Congress,{{cite news |url=https://www.washingtonpost.com/powerpost/republicans-skeptical-about-paying-for-wall-as-trump-prepares-to-release-budget/2017/03/15/dd2b5848-099b-11e7-b77c-0047d15a24e0_story.html |title=Republicans skeptical about paying for wall as Trump releases budget |first1=Sean |last1=Sullivan |first2=Kelsey |last2=Snell |date=March 16, 2017 |access-date=April 9, 2018 |newspaper=Washington Post |url-access=limited}} the U.S. Congress had not appropriated funding for a wall, and no further wall construction had started beyond what was already planned during the Obama administration.

In June 2018, the Trump administration established a new policy of separating parents from their children at the Mexican border. People asking for asylum at official ports of entry were "being turned away and told there's no room for them now."{{Cite web |url=https://www.vox.com/policy-and-politics/2018/6/5/17428640/border-families-asylum-illegal |title=Trump keeps making it harder for people to seek asylum legally |publisher=Vox |date=June 5, 2018 |access-date=June 20, 2018}} The U.S. and Mexico mutually placed tariffs on each other's exports.{{cite news |last1=Aleem |first1=Zeeshan |title=Trump hit Mexico with steel tariffs. Mexico is hitting back – and targeting Republicans |url=https://www.vox.com/world/2018/6/6/17433654/mexico-tariffs-us-goods-trump-trade |access-date=March 7, 2019 |website=Vox |date=June 6, 2018}}

File:Cerco fronterizo de H. Nogales y Nogales.jpg

On November 8, 2018, the Trump administration announced new rules to deny asylum to anyone who crosses into the U.S. illegally from any nation, at Trump's discretion. This was based on the Supreme Court decision of Trump v. Hawaii and the presidential powers of the Immigration and Nationality Act of 1965.{{cite web |url=https://www.nytimes.com/2018/11/08/us/politics/trump-asylum-seekers-executive-order.html |title=Trump Claims New Power to Bar Asylum for Immigrants Who Arrive Illegally |first=Michael |last=Shear |date=November 8, 2018 |access-date=December 21, 2018 |work=The New York Times |url-access=limited}} Trump signed a proclamation the next day to specify that people crossing the Mexican border illegally would not qualify for asylum; he called the march of migrants from Central America towards the U.S. a "crisis".{{cite web |url=https://www.nytimes.com/2018/11/09/us/politics/trump-asylum-seekers-executive-order.html |title=Trump Suspends Some Asylum Rights, Calling Illegal Immigration 'a Crisis' |first1=Michael |last1=Shear |first2=Eileen |last2=Sullivan |date=November 9, 2018 |access-date=December 21, 2018 |work=The New York Times |url-access=limited}} Civil rights groups strongly criticized the move, and several groups, including the Southern Poverty Law Center, the American Civil Liberties Union, and the Center for Constitutional Rights, filed a lawsuit in the U.S. District Court for the Northern District of California to challenge the proclamation. Judge Jon S. Tigar ruled in favor of the advocacy groups on November 20, 2018, placing an injunction on the administration to delay implementation of the rule.{{cite web |url=https://www.nytimes.com/2018/11/20/us/judge-denies-trump-asylum-policy.html |title=Federal Judge Blocks Trump's Proclamation Targeting Some Asylum Seekers |first=Miriam |last=Jordan |date=November 20, 2018 |access-date=December 21, 2018 |work=The New York Times |url-access=limited}} The administration appealed to the Ninth Circuit, where a divided 2–1 panel ruled that the new asylum rules were inconsistent with existing law and upheld the injunction.{{cite web |url=https://apnews.com/1833470d0588418b9c686a61a5de662e |title=US appeals court won't immediately allow Trump asylum ban |date=December 7, 2018 |access-date=April 26, 2020 |website=AP News |first=Sudhin |last=Thanawala}} On December 21, 2018, the Supreme Court declined to hear the administration's challenge, leaving the injunction in place and preventing the asylum ban from being enforced.{{cite web |url=https://www.cnn.com/2018/12/21/politics/supreme-court-upholds-block-on-trumps-asylum-ban/index.html |title=Supreme Court upholds block on Trump's asylum ban |first1=Caroline |last1=Kelly |first2=Ariane |last2=de Vogue |date=December 21, 2018 |access-date=December 21, 2018 |work=CNN}}

During the 2018 fiscal year, U.S. border agents arrested 107,212 people traveling in families, a record-high number. During the following five months (October 2018 through February 2019), that record was shattered by the arrest of 136,150 people traveling in families.{{cite web |title=U.S. Border Patrol Southwest Border Apprehensions by Sector FY2018 |url=https://www.cbp.gov/newsroom/stats/usbp-sw-border-apprehensions |website=U.S. Customs and Border Protection |access-date=March 7, 2019}} On March 31, 2019, Trump threatened to close the border, cutting off trade between the countries.{{Cite news |url=https://www.usatoday.com/story/news/politics/2019/04/01/trump-cutting-aid-closing-ports-border-patrol-stressed-migrant-families-released/3329728002/ |title=Cutting aid and closing ports: Here's what's happening at the southern border |website=USA Today |language=en |access-date=April 1, 2019 |first=Alan |last=Gomez |date=April 1, 2019}} On April 4, Trump said that instead he would give Mexico a year to stop illegal drugs from coming into the U.S. If this did not happen, he said tariffs on automobiles would be used first, and then closing of the border.{{cite news |url=https://www.usatoday.com/story/news/politics/2019/04/04/border-trump-says-he-delay-sealing-off-southern-border-year/3353761002/ |title=President Trump says he will delay closing the border with Mexico for a year |last1=Collins |first1=Michael |last2=Fritze |first2=John |last3=Jackson |first3=David |work=USA Today |date=April 4, 2019 |access-date=April 26, 2020}}

File:United States-Mexico-border-wall-Progreso-Lakes-Texas.jpeg]]

While running for president, Trump estimated that a border wall would cost $8 to $12 billion{{cite magazine |last1=Bennett |first1=Brian |last2=Berenson |first2=Tessa |last3=Abramson |first3=Alana |title=How Republicans Are Talking Trump Into Accepting a Smaller Border Wall Deal |url=https://time.com/5528673/donald-trump-congress-border-security-compromise-republicans/ |access-date=April 26, 2020 |magazine=Time |date=February 13, 2019}} and that he could force Mexico to pay for it. Cost estimates of the proposed wall vary widely. In early 2017, shortly after Trump took office, the DHS estimated the cost at $22 billion,{{cite news |last1=Greenwood |first1=Max |title=DHS report pegs cost of border wall at up to $21.6 billion: report |url=https://thehill.com/business-a-lobbying/318841-dhs-report-pegs-cost-of-border-wall-as-high-as-216-billion-report |access-date=March 7, 2019 |newspaper=The Hill |date=February 9, 2017}} while Democratic staff on the Senate Homeland Security and Governmental Affairs Committee estimated $70 billion to build the wall and $150 million in annual maintenance.{{cite news |last1=Carney |first1=Jordain |title=Senate Dems: Trump's border wall could cost nearly $70 billion |url=https://thehill.com/blogs/floor-action/senate/329359-senate-dems-trumps-border-wall-could-cost-nearly-70-billion |access-date=March 7, 2019 |newspaper=The Hill |date=April 18, 2017}}

In the summer of 2017, four major construction companies planned to bid for the contract. The Customs and Border Protection agency budgeted $20 million to hire these companies to build half-million-dollar prototypes of the wall. At this time, Congress had only approved $341 million to maintain the existing wall; no funds had been allocated to build new sections of wall.{{cite news |url=https://www.nytimes.com/2017/08/31/us/mexico-wall-prototypes-trump.html |title=U.S. Moves to Build Prototypes for Mexican Border Wall |newspaper=The New York Times |first=Ron |last=Nixon |date=August 31, 2017 |access-date=August 27, 2018 |url-access=limited}} The DHS recommended that the wall's height should be between {{cvt|18.|and|30.|ft|abbr=off|order=flip|sigfig=2}} and its depth should be up to {{cvt|6.|ft|order=flip}} to deter drug traffickers from building tunnels.{{cite web |title=The Wall: The real costs of a barrier between the United States and Mexico |first=Vanda |last=Felbab-Brown |date=August 2017 |url=https://www.brookings.edu/essay/the-wall-the-real-costs-of-a-barrier-between-the-united-states-and-mexico/ |website=The Brookings Institution |access-date=April 26, 2020}}

During the Trump administration, {{Convert|455|mi|abbr=on|order=flip}} were added to barrier between the two countries. The construction of the wall has been halted by President Joe Biden as he canceled the national emergency declaration, originally used by Trump.{{Cite news |last1=Miroff |first1=Nick |last2=Hernandez |first2=Arelis R. |date=January 20, 2021 |title=Biden orders a 'pause' on border wall construction, bringing crews to halt |language=en-US |newspaper=Washington Post |url=https://www.washingtonpost.com/national/biden-border-wall-executive-order/2021/01/20/5f472456-5b32-11eb-aaad-93988621dd28_story.html |access-date=October 25, 2021 |issn=0190-8286}}

The U.S. Border Patrol detained more than 1.7 million migrants crossing the U.S.-Mexico border illegally in fiscal year 2021, the highest number ever recorded.{{cite news |title=Record high migrant detentions at US-Mexico border |url=https://www.bbc.com/news/world-us-canada-59019791 |work=BBC News |date=October 23, 2021}}{{cite news |title=Situation at the southern border worse that you probably realize |url=https://thehill.com/opinion/immigration/581513-situation-at-the-southern-border-worse-that-you-probably-realize |work=The Hill |date=November 15, 2021}} A greater demographic diversity of southwest border apprehensions was noted in 2021.Stef W. Kight. (January 30, 2022). "U.S. border draws migrants from Russia, Ukraine".

[https://www.axios.com/us-border-migrants-russia-ukraine-651b35ab-8cf1-480c-afe5-8961e9c98e45.html Axios website] Retrieved January 31, 2022.

On October 31, 2023, Homeland Security Secretary Alejandro Mayorkas testified before the Senate Homeland Security Committee that more than 600,000 people illegally made their way into the United States without being apprehended by border agents during the 2023 fiscal year.{{cite news |title=WATCH LIVE: FBI Director Wray, DHS head Mayorkas testify in Senate hearing on threats to U.S. |url=https://www.youtube.com/watch?v=ZKn948LUX8I&ab_channel=PBSNewsHour |work=PBS NewsHour |date=October 31, 2023 |access-date=December 11, 2023 |archive-date=December 11, 2023 |archive-url=https://web.archive.org/web/20231211102151/https://www.youtube.com/watch?v=ZKn948LUX8I&ab_channel=PBSNewsHour |url-status=live}}

On January 17, 2024, a Republican-led non-binding resolution denouncing the Biden-Harris administration's handling of the U.S. southern border passed the House of Representatives by a vote of 225–187, with 211 Republicans and 14 Democrats supporting it.{{cite web |last1=Adragna |first1=Anthony |title=14 Dems vote with GOP as House condemns Biden handling of southern border |url=https://www.politico.com/live-updates/2024/01/17/congress/house-gop-biden-border-rebuke-dems-00136221 |publisher=Politico |access-date=28 September 2024 |date=17 January 2024}}{{cite web |title=H. RES. 957 |url=https://www.govinfo.gov/content/pkg/BILLS-118hres957ih/pdf/BILLS-118hres957ih.pdf |publisher=118th Congress |access-date=28 September 2024 |date=11 January 2024}}{{cite web |last1=Schnell |first1=Mychael |title=These 14 Democrats voted for a GOP resolution denouncing Biden's 'open-border policies' |url=https://thehill.com/homenews/house/4414955-democrats-gop-resolution-denouncing-biden-open-border-policies/ |work=The Hill |access-date=28 September 2024 |date=17 January 2024}}

On February 8, 2024, a group of 24 House Republicans wrote a letter{{Cite web |title=Letter - PDF |url=https://weber.house.gov/uploadedfiles/border_letter_to_potus_final.pdf}} to urge President Biden not to federalize the Texas National Guard in the midst of Texas wanting to crack down on the spike of illegal immigration on the U.S.-Mexico border.{{Cite web |last=Timotija |first=Filip |date=February 8, 2024 |title=Republicans tell Biden not to take control of Texas National Guard amid standoff over border |url=https://thehill.com/homenews/house/4456459-republicans-biden-not-take-control-texas-national-guard-border/ |access-date=February 9, 2024 |website=The Hill |language=en-US}}

On February 13, 2024, Secretary of Homeland Security Mayorkas was impeached on a 214–213 party-line vote by the United States House of Representatives over his handling of the Mexico–United States border.{{cite web |last1=Grayer |first1=Annie |last2=Foran |first2=Clare |last3=Wilson |first3=Kristin |title=House impeaches Alejandro Mayorkas, first Cabinet secretary to be impeached in almost 150 years |url=https://edition.cnn.com/2024/02/13/politics/alejandro-mayorkas-impeachment-vote/index.html |publisher=CNN |access-date=28 September 2024 |date=13 February 2024}}

On July 25, 2024, the United States House of Representatives voted 220–196 to pass another Republican-led resolution condemning the Biden-Harris administration for their handling of the U.S. southern border. Six Democrats, all in electorally competitive districts, voted with all Republicans in the House to pass the resolution. Democratic Caucus Chair Pete Aguilar said Republicans were playing politics and that the resolution "isn't moving the needle with voters," so members vote how they need to vote.{{cite web |last1=Solender |first1=Andrew |title=A half-dozen Democrats vote to condemn Harris on the border |url=https://www.axios.com/2024/07/25/house-democrats-resolution-kamala-harris-border |publisher=Axios |access-date=28 September 2024 |date=25 July 2024}}{{cite web |last1=Carney |first1=Jordain |last2=Adragna |first2=Anthony |title=Half-dozen Dems join GOP in condemning Harris' work on the border |url=https://www.politico.com/live-updates/2024/07/25/congress/house-condemns-harris-on-border-00171124 |publisher=Politico |access-date=28 September 2024 |date=25 July 2024}}

File:Water Stations at Border.jpg

Humanitarian groups such as Humane Borders, No More Deaths, and Samaritans provide water in order to reduce deaths of immigrants who are journeying through the Arizona desert.{{Cite news |url=http://tucson.com/news/local/border/us-allows-new-water-stations-by-border/article_a8dc1191-74fc-5a8a-9ad0-409b7a1e8b65.html |title=US allows new water stations by border |last=Star |first=Brady McCombs Arizona Daily |work=Arizona Daily Star |access-date=April 6, 2018 |language=en}} A policy passed in 2010 by the U.S. Fish and Wildlife federal agency allows water drums to be placed on roads of disturbed areas.

No More Deaths (No Más Muertes) is a non-governmental organization (NGO) headquartered in Tucson that is designed to assist in ending death and suffering of immigrants along the U.S.-Mexico border by upholding fundamental human rights. Elemental services of No More Deaths is to provide humanitarian assistance, giving food and first aid treatment, witness and respond to human rights abuses, encouraging humane immigration policy, and making phone calls to relatives of immigrants.{{Cite journal |last=Bird |first=Jo |date=November 2014 |title=Human Rights on the US/Mexico Border |journal=Pandora's Box (1835-8624) |volume=21 |pages=94–101}} Since its founding in 2004, No More Deaths has provided assistance to thousands of migrant border crossers; however the Border Patrol and other public land agencies near the U.S.–Mexico border have challenged the efforts of various humanitarian groups, by following immigrants to a medical volunteer camp and raiding it.{{Cite news |url=https://www.statnews.com/2017/07/06/immigration-desert-clinic/ |title=After Trump's immigration crackdown, a desert clinic tries to save lives without breaking the law |last=Boodman |first=Eric |date=July 6, 2017 |work=STAT |access-date=December 1, 2018}} Humanitarian groups along the border have been tested by Border Patrol and other agencies, however the authority of the Trump administration has introduced a new tier of restriction through surveillance, harassment, and intimidation to border relief efforts.{{Cite journal |last=Smith |first=Sophie |date=October 2017 |title=No More Deaths: Direct Aid in the US-Mexico Border Zone |journal=South Atlantic Quarterly |volume=116 |pages=851–862 |doi=10.1215/00382876-116-4-851}}

File:Tijuana-san diego border deaths.jpg

Incidence rates of HIV and tuberculosis are higher in border towns such as El Paso and Ciudad Juárez than at the national level in both countries. The Nuestra Casa Initiative tried to counter the health disparities by using a cross-border strategy that moved around an exhibit prominent in various museums and universities.Moya, Eva, et al. "Nuestra Casa: An Advocacy Initiative to Reduce Inequalities and Tuberculosis along the US–Mexico Border." International Public Health Journal, vol. 8, no. 2, 2016, pp. 107–119.{{cite journal |last1=Moya, Eva |last2=Chavez-Baray, Silvia |last3=Wood, William W. |last4=Martinez, Omar |title=Nuestra Casa: An advocacy initiative to reduce inequalities and tuberculosis along the US–Mexico border |journal=International Public Health Journal |date=2016 |volume=8 |issue=2 |pages=107–119 |language=en |issn=1947-4989 |pmid=30245778 |pmc=6150456}} Similarly, special action groups as part of the Border Health Strategic Initiative created by the University of Arizona with other groups helped create a healthier Hispanic community in Arizona border towns by creating policy and infrastructure changes.{{cite journal |last1=Cohen |first1=Stuart J. |last2=Meister |first2=Joel S. |last3=deZapien |first3=Jill G. |title=Special Action Groups for Policy Change and Infrastructure Support to Foster Healthier Communities on the Arizona–Mexico Border |journal=Public Health Reports |volume=119 |issue=1 |year=2016 |pages=40–47 |issn=0033-3549 |doi=10.1177/003335490411900110 |pmid=15147648 |pmc=1502256}} These groups provided humanitarian assistance to counter the prominence of Type 2 diabetes among the Hispanic community by acquiring a grant for new walking trails and encouraging public elementary schools to provide healthier food choices for students.

Immigrants are considered easy targets by gang members, because they do not have the strength to resist aggressive offenders and end up left with nothing. In June 2018, U.S. Attorney General Jeff Sessions disqualified victims of gangs or domestic violence to be reasonable causes for asylum seekers.{{Cite magazine |last=Rhodan |first=Maya |date=November 2018 |title=Give Me Shelter |magazine=Time |volume=192 |pages=36–41}}

File:BigBendMexicans.jpeg]]

Not only do these Hispanic communities face health inequalities, but political inequalities as well.{{cite news |first=Suzanne |last=Gamboa |date=February 26, 2019 |title=Racism, not a lack of assimilation, is the real problem facing Latinos in America |website=NBC News |url=https://www.nbcnews.com/news/latino/racism-not-lack-assimilation-real-problem-facing-latinos-america-n974021}} The need for political change was so huge that it has encouraged Hispanic women to engage in activism at a local level. The Neighborhood Action Group in Chula Vista, California, is one of the groups that attracted the help of local Hispanic women to implement a feminist perspective in activism in spite of the social and economic obstacles as well as Assembly Bill No. 775, 2005 that prohibited children being used as interpreters.{{cite journal |last1=Bosco |first1=Fernando J. |last2=Aitken |first2=Stuart C. |last3=Herman |first3=Thomas |title=Women and children in a neighborhood advocacy group: engaging community and refashioning citizenship at the United States–Mexico border |journal=Gender, Place & Culture |volume=18 |issue=2 |year=2011 |pages=155–178 |issn=0966-369X |doi=10.1080/0966369X.2010.551652 |s2cid=144414124}} These humanitarian groups have implemented various strategies to pursue their goals that ultimately try to counter the number of immigrant deaths and abuses in immigrant detention even if it means the criminalization and higher levels of discrimination against them.{{cite journal |last1=Androff |first1=D. K. |last2=Tavassoli |first2=K. Y. |title=Deaths in the Desert: The Human Rights Crisis on the U.S.–Mexico Border |journal=Social Work |volume=57 |issue=2 |year=2012 |pages=165–173 |issn=0037-8046 |doi=10.1093/sw/sws034 |url=https://asu.pure.elsevier.com/en/publications/deaths-in-the-desert-the-human-rights-crisis-on-the-us-mexico-bor |pmid=23038878}}

In Mexico, most humanitarian groups focus on assisting the deportees. As rates of deportation increase, "the deportation of many individuals is becoming more and more notable" in the streets of Mexico cities.{{Cite web |url=http://www.atencionsanmiguel.org/2018/02/16/new-organization-emerges-to-aid-deported-mexican-nationals/ |title=New Organization Emerges to Aid Deported Mexican Nationals {{!}} San Miguel de Allende {{!}} Atención San Miguel |website=Atencionsanmiguel.org |language=en-US |access-date=April 6, 2018 |archive-date=April 7, 2018 |archive-url=https://web.archive.org/web/20180407054208/http://www.atencionsanmiguel.org/2018/02/16/new-organization-emerges-to-aid-deported-mexican-nationals/ |url-status=dead}} As a result, many humanitarian groups have formed in Mexican cities where undocumented individuals are deported such as Nogales, Sonora. The humanitarian groups consist of faith-based communities and primarily non-profit organizations that assist deportees, many of whom do not have any resources with them such as money, food, or family information, and who would otherwise become homeless and emotionally and psychologically devastated.{{Cite AV media |last=Burr |first=Pete |title=Kino Border Initiative – the church without frontiers |date=February 28, 2017 |url=https://vimeo.com/206180020 |access-date=April 6, 2018 |via=Vimeo}}{{Cite web |url=http://www.qeh.ox.ac.uk/content/humanitarianism-ground-humanitarian-aid-migrants-and-refugees-mexico |title=Humanitarianism from the ground: humanitarian aid to migrants and refugees in Mexico {{!}} Oxford Department of International Development |website=Qeh.ox.ac.uk |language=en |access-date=April 6, 2018 |archive-date=April 7, 2018 |archive-url=https://web.archive.org/web/20180407055211/http://www.qeh.ox.ac.uk/content/humanitarianism-ground-humanitarian-aid-migrants-and-refugees-mexico |url-status=dead}} Contributing factors that might have caused them to be devastated can either be that they were separated from "their family members or the inability to work legally in the United States".{{Cite web |url=https://www.kinoborderinitiative.org |title=Kino Border Initiative – Iniciative Kino para la Frontera |website=Kino Border Initiative |language=en-US |access-date=April 6, 2018}} Therefore, the primary purpose of the humanitarian groups on the Mexico side of the border is to create a pathway for transitional support such as providing the deportees food, shelter, clothing, legal help and social services. In addition, there are humanitarian groups that provides meals and shelter to deportees according to their deportation documents. Humanitarian groups along the border in Mexico are El Comedor, Nazareth House, Camino Juntos, La 72, and FM4: Paso Libre.

In June 2019, 300 migrant children were moved from a detention facility in Clint, Texas, after a group of lawyers who visited reported unsafe and unsanitary conditions. In the same month, the body of Óscar Alberto Martínez and his 23-month-old daughter, Angie Valeria, were found dead in the Rio Grande River. The family was from El Salvador, attempting to cross from Mexico into the U.S. near Brownsville, Texas.{{cite news |first1=Christina |last1=Maxouris |first2=Steve |last2=Almasy |first3=Natalie |last3=Gallón |date=June 27, 2019 |title=A woman watched her husband and daughter drown at the Mexican border, report says |url=https://www.cnn.com/2019/06/26/politics/mexico-father-daughter-dead-rio-grande-wednesday/ |website=CNN}} Gaining attention from the media, the House passed a bill, appropriating $4.5 billion for resources at the border.{{cite news |first1=Rebecca |last1=Shabad |first2=Leigh Ann |last2=Caldwell |date=June 25, 2019 |title=House passes border funding bill to address humanitarian crisis |website=NBC News |url=https://www.nbcnews.com/politics/congress/house-passes-border-funding-bill-address-humanitarian-crisis-n1021511}}

{{See also|Politics of the Arizona Borderlands|California Border Police Initiative|A Proclamation on Securing the Border}}

Per the La Paz Agreement,{{cite web |url=https://www.epa.gov/sites/production/files/2015-09/documents/lapazagreement.pdf |title=La Paz Agreement |website=Epa.gov |access-date=April 9, 2018}} the official "border area" extends {{convert|100.|km|mi|abbr=on}} "on either side of the inland and maritime boundaries" from the Gulf of Mexico west into the Pacific Ocean. There is also a 100-mile border zone.

{{One source section|date=June 2018}}

File:Defense.gov photo essay 060719-A-3715G-077.jpg member working with the U.S. Border Patrol in support of Operation Jump Start, Arizona, July 2006]]

A National Border Patrol Strategic Plan was first developed in 1994; it was then updated in 2004 and 2012. In 2004, the updated strategy focused on command structures, intelligence and surveillance, enforcement and deployment of U.S. Border Patrol agents to better respond to threats at the border. The strategic planning led to broader policy development for the DHS which led to the Secure Border Initiative (SBI) in 2005 to secure U.S. borders and reduce illegal migration. The main components of SBI dealt with staffing concerns, removal capacity, surveillance and tactical infrastructure and interior enforcement.{{cite journal |last1=Seghetti |first1=Lisa |title=Border Security: Immigration Enforcement Between Ports of Entry |journal=Congressional Research Service |date=December 31, 2014 |url=https://www.fas.org/sgp/crs/homesec/R42138.pdf}} The aim of this initiative is to overcome the limitations of physical barriers through the use of surveillance technologies known as "SBInet."{{Cite news |date=April 15, 2010 |title=The Rise and Fall of the Secure Border Initiative's High-Tech Solution to Unauthorized Immigration |url=https://www.americanimmigrationcouncil.org/research/rise-and-fall-secure-border-initiative%E2%80%99s-high-tech-solution-unauthorized-immigration |access-date=October 26, 2022 |website=American Immigration Council |language=en}} The SBInet technology has not worked as well as potentially intended, facing a number of technical issues that have limited its effectiveness. Part of the initiative also focused on increasing detention and removal capacity, with an objective to add an additional 2,000 beds to detentional facilities.{{Cite web |title=Fact Sheet:Secure Border Initiative |url=https://www.hsdl.org/?view&did=440470 |access-date=October 26, 2022 |website=Homeland Security Digital Library |language=en-US}} With expansion of detention and removal capabilities this was also the objective to end the "catch and release" process that had been occurring previously. An additional component was "high consequence enforcement", which was not the subject of a formal public policy document. There was the allowance, historically, for voluntary returns of individuals apprehended at the border by Border Patrol agents. These voluntary returns, after the SBI of 2005, were limited to three "high consequence outcomes".

One "high consequence outcome" was formal removal, which meant the individual would be deemed ineligible for a visa for at least five years and subject to criminal charges if caught re-entering illegally. The Immigration and Nationality Act permitted aliens to be formally removed with "limited judicial processing" known as expedited removal. The DHS has expanded between 2002 and 2006, expedited removal for "certain aliens that entered within previous two weeks and were apprehended within {{convert|100.|mi|abbr=on|order=flip}} of the border".{{Page needed|date=March 2023}}

Another "high consequence outcome" is the increase in criminal charges. The DHS has also worked with the U.S. Department of Justice (DOJ) to increase the number of apprehended individuals crossing the border illegally who are charged with criminal offenses. Most of these cases are prosecuted under Operation Streamline. The third "high consequence outcome" is known as remote repatriation. This is the return of apprehended Mexicans to remote locations by Border Patrol rather than the nearest Mexican port of entry.

{{main|Border search exception}}

{{more citations needed section|date=March 2015}}

File:USMC-10343.jpg monitoring the U.S.–Mexico border in southwest Arizona]]

The U.S. has established a {{Convert|100.|mi|km|abbr=on|adj=on|order=flip}} border zone which applies to all U.S. external borders including all coasts, in effect covering two-thirds of the U.S. population,{{Cite web |author=Catherine E. Shoichet |url=https://edition.cnn.com/2018/05/23/us/border-zone-immigration-checks/index.html |title=The US border is bigger than you think |publisher=CNN |date=May 24, 2018 |access-date=July 16, 2018}} including a majority of the largest cities in the U.S. and several entire states (namely Connecticut, Delaware, Florida, Hawaii, Maine, Michigan, New Hampshire, New Jersey, and Rhode Island). The border zone was established by the U.S. DOJ in its interpretation of the Immigration and Nationality Act of 1952.{{cite journal |title=The Constitution in the 100-Mile Border Zone |journal=American Civil Liberties Union |url=https://www.aclu.org/immigrants-rights/constitution-100-mile-border-zone}} Customs and Border Protection (CBP) officials have authority to stop and search within this zone and are authorized to enter private property without a warrant within {{convert|25|mi|km|abbr=on|order=flip}} of the border as well as establish checkpoints.{{cite journal |last1=Rickerd |first1=C. |title=Customs and Border Protection's (CBP's) 100-Mile Rule |journal=American Civil Liberties Union |url=https://www.aclu.org/sites/default/files/assets/13_08_01_aclu_100_mile_cbp_zone_final.pdf}}

The Fourth Amendment of the U.S. Constitution protects against unreasonable search and seizure. However, under the border search exception, this protection does not fully apply at borders or border crossings (also known as ports of entry) or in the border zone. This means that much of the U.S. population is subject to CBP regulations including stop and search. There are some limits to CBP officials' ability to stop and search. For instance CBP officials are not allowed to pull anyone over without a reasonable suspicion of immigration violation or crime, or search vehicles without warrant or probable cause. The ACLU, however, found that CBP officials routinely ignore or misunderstand the limits of authority, and this is compounded by inadequate training, lack of oversight and failure to hold officials accountable for abuse—incidence of abuse is common.

File:Tucson Federal Courthouse.jpg

Operation Streamline refers collectively to zero-tolerance policies implemented at the Mexico–U.S. border that seek to remove illegal immigrants through an expedited process if they have arrived with missing or fraudulent identification or have previously been convicted for an immigration crime.{{cite journal |last1=Lydgate |first1=L. |title=Assembly-Line Justice: A Review of Operation Streamline |journal=California Law Review |date=2010 |volume=98 |issue=2 |pages=481–544 |jstor=20743978}} It was first implemented in Del Rio, Texas, in 2005.{{cite journal |last1=Nazarian |first1=E. |title=Crossing Over: Assessing Operation Streamline and the Rights of Immigrant Criminal Defendants at the Border |journal=Loyola of Los Angeles Law Review |date=2011 |volume=44 |pages=1399–1430 |url=http://heinonline.org/HOL/Page?handle=hein.journals/lla44&collection=journals&page=1399 |archive-url=https://web.archive.org/web/20180623193834/https://heinonline.org/HOL/Page?handle=hein.journals%2Flla44&collection=journals&page=1399 |archive-date=June 23, 2018 |hdl=hein.journals/lla44 |access-date=October 13, 2020 |url-status=live}} [http://digitalcommons.lmu.edu/cgi/viewcontent.cgi?article=2761&context=llr Alt URL] The program has since expanded to four out of the five federal judicial districts on the U.S.–Mexico border: Yuma, Arizona; Laredo, Texas; Tucson, Arizona; and Rio Grande Valley, Texas.{{cite journal |last1=Kerwin |first1=D. |last2=McCabe |first2=K. |title=Arrested on Entry: Operation Streamline and the Prosecution of Immigration Crimes |date=April 29, 2010 |url=http://www.migrationpolicy.org/article/arrested-entry-operation-streamline-and-prosecution-immigration-crimes |journal=Migration Policy Institute}}

Previously, immigrants apprehended at the border were either given the option to voluntarily return to their home country or they were placed in civil immigration proceedings. After Operation Streamline was implemented, nearly all people apprehended at the border who are suspected of having crossed illegally are subject to criminal prosecution. Defendants who are charged with crossing into the U.S. illegally are tried en masse to determine their guilt. Defense attorneys often are responsible for representing up to 40 immigrants at once. Around 99% of defendants in Operation Streamline proceedings plead guilty. The defendants are charged with a misdemeanor if convicted of crossing the border illegally for the first time and a felony if it is a repeat offense.

In December 2009, it was decided in United States v. Roblero-Solis that en masse judicial proceedings like those in Operation Streamline violated Rule 11 in the Federal Rules of Criminal Procedure. Rule 11 states that the court must determine that a guilty plea is voluntarily made by addressing the defendant personally in court. The Roblero-Solis case determined that "personally" means that the judge must address the defendant in a person-to-person manner. Though many courts have changed their procedures to adapt to the ruling, there are still forms of en masse trials practiced at the border.

File:ICE Arrest.jpg officers deporting a man wanted for two murders in Mexico]]

Proponents of Operation Streamline claim that the harsher prosecution has been an important factor in deterring immigrants from crossing the border illegally. Apprehensions have decreased in certain sectors after 2005, which is seen as a sign of success. For example, the Del Rio sector saw a decline from 2005 to 2009 of 75% (from 68,510 to 17,082). Similarly, apprehensions declined in Yuma by 95% (from 138,438 to 6,951) from 2006 to 2009.

Criticisms of Operation Streamline point to the program's heavy use of federal court and enforcement resources as a negative aspect. In addition, the prosecution of all illegal border crossings takes the focus away from prosecuting more serious crimes. They claim that the program's cost is too high for the effectiveness of the work it is accomplishing. In response to the claim that Operation Streamline is an effective deterrent, critics of the program claim that the incentives to cross the border in order to work or be with family are much stronger.

{{More|Environmental issues along the Mexico–United States border}}

The Agreement on Cooperation for the Protection and Improvement of the Environment in the Border Area, known as the La Paz Agreement, was signed into law on August 14, 1983, and became enforceable on February 16, 1984.{{cite web |url=http://www.epa.gov/Border2012/docs/LaPazAgreement.pdf |title=Agreement on Cooperation for the Protection and Improvement of the Environment in the Border Area |year=1983 |access-date=December 2, 2014 |publisher=US Environmental Protection Agency}} This agreement to protect the environment is the political foundation between the U.S. and Mexico for 4 subsequent programs. Each program has addressed environmental destruction in the border region resulting from the rise of the maquiladora industries, those who migrated to northern Mexico to work in the industries, the lack of infrastructure to accommodate the people, Mexico's lax regulations concerning all these factors, the resulting spillover into the U.S., and the U.S.'s own environmentally destructive tendencies. The programs were: IBEP (1992), Border XXI (1996), Border 2012 (2003) and Border 2020 (2012).{{cite web |last=Smith |first=Colin |title=1 U.S.  – Mexico Cooperation for the Health of the Environment in the Border Region: A Policy History Analysis |url=https://www.academia.edu/2640698 |archive-url=https://archive.today/20131113160840/http://www.academia.edu/2640698/U.S._-_Mexico_Cooperation_for_the_Health_of_the_Environment_in_the_Border_Region_A_Policy_History_Analysis |url-status=dead |archive-date=November 13, 2013}}

{{one source|section

| date = June 2018

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File:Mexico-US border at Tijuana.jpg

In 2006, during the presidency of George W. Bush, Congress approved Secure Fence Act which allowed the Department of Homeland Security to erect a border fence along the U.S.–Mexico border. Congress also approved a different law called the REAL ID Act which gave the Department of Homeland Security the approval to build the wall without taking into consideration the environmental and legal issues related to the wall. The U.S. Congress insisted that the act was passed for the sake of national security of the U.S.{{cite journal |last1=Cohn |first1=Jeffrey P. |title=The Environmental Impacts of a Border Fence |journal=BioScience |volume=57 |issue=1 |year=2007 |pages=96 |issn=1525-3244 |doi=10.1641/B570116 |jstor=10.1641/b570116 |s2cid=84341799 |doi-access=free}}

According to a delegation of Arizona park and refuge managers, wildlife biologists, and conservationists who studied the U.S. and Mexico border concluded that building a wall along the Mexico border would also have negative impacts on the natural environment in the region. They argued that the border wall would negatively affect the wildlife in the Sonoran Desert including plants and animals. Naturally, animals do not tend to stay in one place and instead, they expedite to various places for water, plants, and other means in order to survive. The wall would restrict animals to a specific territory and would reduce their chances of survival. According to Brian Segee, a staff attorney with Wildlife Activists says that except high flying birds, animals would not be able to move to other places because of the wall along the border. For instance, participants in this study argued that some species such as javelinas, ocelots, and Sonoran pronghorn would not be able to freely move along the border areas. It would also restrict the movement of jaguars from Sierra Madre occidental forests to the southwestern parts of the U.S. According to Brian Nowicki, a conservation biologist at the Center for Biological Diversity, there are 30 animal species living in the Arizona and Sonora that face danger. In 2021, an endangered Mexican gray wolf was stopped from crossing from New Mexico into Mexico by a section of border wall.{{Cite web |url=https://www.nationalgeographic.com/animals/article/mexican-gray-wolf-migration-stopped-by-border-wall |archive-url=https://web.archive.org/web/20220121231517/https://www.nationalgeographic.com/animals/article/mexican-gray-wolf-migration-stopped-by-border-wall |url-status=dead |archive-date=January 21, 2022 |title=An endangered wolf went in search of a mate. The border wall blocked him |website=National Geographic Society |date=January 21, 2022}}

{{Seealso|Illegal drug trade in Latin America|Illegal drug trade in the United States|Crime in Mexico|Mexican drug war|Opioid epidemic in the United States}}

Mexico is estimated to be the world's third largest producer of opium with poppy cultivation. It also is a major supplier of heroin and the largest foreign supplier of marijuana, cocaine and methamphetamine to the U.S. market.{{Cite web |url=https://www.cia.gov/the-world-factbook/countries/mexico/ |title=The World Factbook — Central Intelligence Agency |website=www.cia.gov |language=en |access-date=2018-01-27}}{{Cite web |url=https://www.dea.gov/divisions/hq/2016/hq120616.shtml |title=DEA.gov / Headquarters News Releases, 12/06/16 |website=www.dea.gov |language=en-US |access-date=2018-01-27}} According to the DEA, about 93% of the cocaine in the United States came from Colombia and was smuggled across the border between Mexico and the United States. In 2017, the INL estimated that "between 90 and 94 percent of all heroin consumed in the United States comes from Mexico."{{cite news |title=Fact-checking Trump on drug traffic from Mexico |url=https://edition.cnn.com/2019/06/01/politics/trump-mexico-drugs-90-percent-tariff-fact-check/index.html |work=CNN |date=June 1, 2019}} These drugs are supplied by drug trafficking organizations. The U.S. government estimates that Mexican drug cartels gain tens of billions of dollars each year from drug sales in the U.S. alone.{{Cite news |url=https://www.cfr.org/backgrounder/mexicos-drug-war |title=Mexico's Drug War |work=Council on Foreign Relations |access-date=2018-01-27 |language=en}}

Border towns on the Mexico–United States border have been negatively affected by the opioid crisis in the United States. According to César González Vaca, head of the Forensic Doctor's Service in Baja California, "It seems the closer we are to the border, the more consumption of this drug we see."{{cite news |title='People will keep dying': Fentanyl crisis grips Mexico's border cities |url=https://www.bbc.com/news/world-latin-america-68101263 |work=BBC News |date=7 February 2024}}{{cite news |title='People will keep dying': Fentanyl crisis grips Mexico's border cities |url=https://www.bbc.com/news/world-latin-america-68101263 |work=BBC News |date=7 February 2024}} In 2021, around 80,411 people died from opioid overdoses in the United States.{{cite news |title=Opioid Deaths Could Hit 165,000 Annually Without Intervention, Biden Official Warns |url=https://www.forbes.com/sites/mollybohannon/2023/06/07/opioid-deaths-could-hit-165000-annually-without-intervention-biden-official-warns/ |work=Forbes |date=June 7, 2023}} Many of the deaths are from an extremely potent opioid, fentanyl, which is trafficked from Mexico.{{cite news |last1=Miroff |first1=Nick |url=https://www.washingtonpost.com/world/national-security/at-the-new-york-division-of-fentanyl-inc-a-banner-year/2017/11/13/c3cce108-be83-11e7-af84-d3e2ee4b2af1_story.html |title=Mexican traffickers making New York a hub for lucrative — and deadly — fentanyl |date=November 13, 2017 |newspaper=The Washington Post |name-list-style=vanc}} The drug is usually manufactured in China, then shipped to Mexico, where it is processed and packaged, which is then smuggled into the United States by Mexican drug cartels.{{Cite web |last=Linthicum |first=Kate |date=2020-04-24 |title=Coronavirus chokes the drug trade — from Wuhan, through Mexico and onto U.S. streets |url=https://www.latimes.com/world-nation/story/2020-04-24/wuhan-china-coronavirus-fentanyl-global-drug-trade |website=Los Angeles Times |language=en-US}} In 2023, the Biden administration announced a crackdown on members of the Sinaloa Cartel smuggling fentanyl into the United States.{{cite news |title=Mexican cartel targeted by Biden administration in multiple fentanyl indictments |url=https://coloradonewsline.com/briefs/mexican-cartel-biden-fentanyl-indictments/ |work=Colorado Newsline |date=April 14, 2023}}

{{more citations needed|date=May 2019}}

File:Nogales-Grand Avenue Port of Entry.jpg

Many schools near the border in America have students that live on the Mexican side of the border. These students are "transborder students", as they live in Mexico but are enrolled in the U.S. education system. There are thousands of elementary through high school students that cross the Mexican-American border. They are known to wake up in the early hours of the morning to make their way to the border, where they wait in long lines to cross into the U.S. After crossing the border, the students find a ride to school. Many students come to America for the opportunity, because it has a more developed and organized educational system. Students who go to school in America have a better chance of reaching higher education in the U.S. In many parts of Mexico, compulsory education ends at age sixteen. Many of the transborder students are natural-born U.S. citizens. Students that were born in America have the right to American education, even if they do not live in the U.S. In places like the San Diego and Tijuana border, it is much cheaper to live in Mexico. San Diego has a high cost of living and one of the highest student homeless rates in the country, so many families move to Tijuana because it is more affordable to raise a family.

In order to prevent Mexican children from illegally coming to America for education, some bordertown schools require official documentation (bills, mail, etc.) from students. This is to ensure that only students that are entitled to an education in the U.S. receive one.

In Brownsville, a city on the southern border of Texas, a court ruled that school districts cannot deny students education if they have the proper paperwork. Many transborder students who live in these districts with these requirements will use extended family members' addresses to prove their residency. Questions about the legitimacy of student residency have risen since the Trump administration took office in 2017, making it riskier to cross the border for education.

These transborder students also raise questions about the acquisition of healthcare, as most Mexican students who attend university in the U.S. who also have family across the border are known to use the Mexican healthcare system instead of U.S. or university sources.{{Cite journal |last1=Fernández |first1=Leticia |last2=Amastae |first2=Jon |date=September 1, 2006 |title=Transborder use of medical services among Mexican American students in a U.S. border university |journal=Journal of Borderlands Studies |volume=21 |issue=2 |pages=77–87 |doi=10.1080/08865655.2006.9695661 |s2cid=143982920 |issn=0886-5655}} The opposite case was also studied, seeking to find if U.S. students and citizens outsource their medical care from Mexican hospitals; however it was concluded that the use of, "cross-border healthcare diminishes significantly with English language acquisition."

Also researched is the impact of changing education for those children who attended school in the U.S. prior to deportation, and are now readjusting to a new education system within Mexico. In one study, when repatriated children were asked about how their world perspectives were changed once they returned to Mexico, they spoke to three main areas, "shifting identities, learning and losing named language, and schooling across borders."{{Cite journal |last=Kleyn |first=Tatyana |date=April 3, 2017 |title=Centering Transborder Students: Perspectives on Identity, Languaging and Schooling Between the U.S. and Mexico |journal=Multicultural Perspectives |volume=19 |issue=2 |pages=76–84 |doi=10.1080/15210960.2017.1302336 |s2cid=149362544 |issn=1521-0960}} The most frequent point mentioned in terms of changing schooling is the difficulty to adapt to a system in which they are unfamiliar, in a named language they might have lost, and where there is minimal continuity in the methodology of teaching. It is suggested in this study that while the U.S. has a long history of teaching immigrant students, along with tried and tested assimilation programming to support foreign children in U.S. border schools, Mexican systems do not, making the change nearly impossible for newly deported students to learn. While the Mexican Secretariat of the Public has vowed to change the legislation surrounding this issue, bilingual education is still only awarded to expensive private schools.

{{Portal|Mexico|United States|Politics}}

• Indigenous conflicts on the Mexico–United States barrier
• 2017 Mexico–United States diplomatic crisis
• Border Protection, Anti-terrorism, and Illegal Immigration Control Act of 2005
• Border War (1910–19)
• Canada–United States border
• Illegal drug trade in the United States
• Illegal immigration to Mexico
• Illegal immigration to the United States
• List of municipalities (municipios) and counties on the Mexico–United States border
• Mexico–United States international park
• Mexico–United States relations
• Operation Jump Start
• Operation Phalanx (2010–2016)
• Roosevelt Reservation
• Spillover of the Mexican drug war
• Secure Fence Act of 2006
• Sexual assault of migrants from Latin America to the United States
• Treaty of Limits (Mexico–United States)
• United States Border Patrol interior checkpoints

{{Reflist}}

{{refbegin|40em}}

• Arbelaez, Harvey, and Claudio Milman. "The New Business Environment of Latin America and the Caribbean". International Journal of Public Administration (2007): 553
• {{cite journal |last1=Arbelaez |first1=Harvey |last2=Milman |first2=Claudio |title=The new business environment of latin america and the caribbean |journal=International Journal of Public Administration |volume=23 |issue=5–8 |year=2000 |pages=553–562 |issn=0190-0692 |doi=10.1080/01900690008525475 |s2cid=154543297}}
• Kelly, Patricia, and Douglas Massey. "Borders for Whom? The Role of NAFTA in Mexico-U.S. Migration". The ANNALS of the American Academy of Political Science 610 (2007): 98–118.
• {{cite journal |last1=Fernández-Kelly |first1=Patricia |last2=Massey |first2=Douglas S. |title=Borders for Whom? The Role of NAFTA in Mexico-U.S. Migration |journal=The Annals of the American Academy of Political and Social Science |volume=610 |issue=1 |year=2016 |pages=98–118 |issn=0002-7162 |doi=10.1177/0002716206297449 |s2cid=154846310}}
• Miller, Tom. On the Border: Portraits of America's Southwestern Frontier, 1981.
• Thompson, Olivia N. (2009). [http://ecommons.txstate.edu/arp/313 "Binational Water Management: Perspectives of Local Texas Officials in the U.S.–Mexico Border Region"]. Applied Research Projects. Texas State University. Paper 313.
• {{Cite journal |last=Thompson |first=Olivia N. |date=2009 |title=Binational Water Management: Perspectives of Local Texas Officials in the U.S.–Mexico Border Region |url=https://digital.library.txstate.edu/handle/10877/3758 |journal=Applied Research Projects. |issue=Paper 313 |hdl=10877/3758}}
• Andrew Becker and Agustin Armendariz. [https://www.huffingtonpost.com/2012/06/22/california-border-crossing_n_1619067.html "California Border Crossing: San Ysidro Port of Entry Is the Busiest Land Border in the World"]. HuffPost social reading, article on California watch. (2012)
• Prampolini, Gaetano, and Annamaria Pinazzi (eds.). "The Shade of the Saguaro/La sombra del saguaro" Part IV 'About the Border{{'"}}. Firenze University Press [http://www.fupress.com/ Firenze University Press] (2013): 461–517.

{{refend}}

• Feldman, Megan (October 16, 2008). [http://www.dallasobserver.com/news/border-town-6373408 "Border Town"]. Dallas Observer.
• Jeremy Slack, Daniel E. Martínez, Scott Whiteford, eds. The Shadow of the Wall: Violence and Migration on the U.S.-Mexico Border. University of Arizona Press, 2018. {{ISBN|978-0816535590}}.

{{Commons}}

• [https://web.archive.org/web/20170906171559/http://usmexico.org/ U.S.–Mexico Business Council]
• [https://www.cdc.gov/usmexicohealth/about-border-region.html About binational health – United States–Mexico Public Health – CDC]
• [http://www.borderstories.org/ Border Stories: a mosaic documentary on the U.S.–Mexico Border]
• [https://fas.org/sgp/crs/misc/R41821.pdf Status of Mexican Trucks in the United States: Frequently Asked Questions] Congressional Research Service
• [http://library.uta.edu/usmexicowar/ A Continent Divided: The U.S.–Mexico War], Center for Greater Southwestern Studies, the University of Texas at Arlington
• Josh Begley, [https://theintercept.com/2016/10/26/best-of-luck-with-the-wall/ Best of Luck with the Wall] – a short film constructed from satellite imagery that traces the length of the border
• David Taylor, [http://www.kcet.org/arts/artbound/counties/san-diego/border-monuments-us-mexico.html The Journey to Border Monument Number 140]{{snd}}photographs and description of the obelisks that mark the border
• The Guardian, [https://www.theguardian.com/artanddesign/2017/feb/23/cut-in-two-travels-along-the-us-mexico-border-a-photo-essay The Guardian]{{snd}}photographs and feature-length film that follows the infrastructure of the border from the Gulf of Mexico to the Pacific Ocean

{{Borders of Mexico}}

{{Borders of the United States}}

{{Immigration to the United States}}

{{Mexico–United States relations}}

{{Authority control}}

United States

Category:Borders of the United States

Category:International borders

Category:Geography of Arizona

Category:Geography of California

Category:Geography of New Mexico

Category:Geography of Texas