Border

In the pre-modern world, the term border was vague and could refer to either side of the boundary, thus it was necessary to specify part of it with borderline or borderland. During the medieval period the government's control frequently diminished the further people got from the capital. Therefore borderland (especially impassable terrain) attracted many outlaws, as they often found sympathizers.{{cite book |last1=Jones |first1=T. |url=https://books.google.com/books?id=7cjHAAAAQBAJ |title=Outlaw in Medieval Literature |date=2010 |publisher=Springer |isbn=9780230114685 |page=51 |language=en |via=Google Books}}

In the past, many borders were not clearly defined lines; instead there were often intervening areas often claimed and fought over by both sides, sometimes called marchlands. Special cases in modern times were the Saudi Arabian–Iraqi neutral zone from 1922 to 1991 and the Saudi Arabian–Kuwaiti neutral zone from 1922 until 1970. In modern times, marchlands have been replaced by clearly defined and demarcated borders.

{{See also|List of countries and territories by land and maritime borders}}

Political borders are imposed on the world through human agency.{{cite journal |last=Robinson |first=Edward Heath |url=http://www.edwardheath.net/wp-content/uploads/2013/01/Reexamining_boundaries.pdf |title=Reexamining Fiat, Bona Fide and Force Dynamic Boundaries for Geopolitical Entities and their Placement in DOLCE |archive-url=https://web.archive.org/web/20131230235301/http://www.edwardheath.net/wp-content/uploads/2013/01/Reexamining_boundaries.pdf |archive-date=30 December 2013 |journal=Applied Ontology |date=2012 |volume=7 |pages=93–108|doi=10.3233/AO-2012-0103 }} That means that although a political border may follow a river or mountain range, such a feature does not automatically define the political border, even though it may be a major physical barrier to crossing.

Political borders are often classified by whether or not they follow conspicuous physical features on the earth. William Miles said that Britain and France traced close to 40% of the entire length of the world's international boundaries.{{cite book |last1=Miles |first1=William F. S. |title=Scars of Partition: Postcolonial Legacies in French and British Borderlands |date=2014 |publisher=U of Nebraska Press |isbn=978-0-8032-6771-8 |page=3 |quote=Anglo-French carving of colonial space is a significant geographical legacy: nearly 40 percent of the entire length of today's international boundaries were traced by Britain and France.}}

File:City Lights at Night along the France-Italy Border.JPG separates the two countries.]]

{{Main|Natural border}}

Natural borders are geographical features that present natural obstacles to communication and transport. Existing political borders are often a formalization of such historical, natural obstacles.

Some geographical features that often constitute natural borders are:

• Oceans: oceans create very costly natural borders. Very few countries span more than one continent. Only very large and resource-rich states are able to sustain the costs of governance across oceans for longer periods of time.
• Rivers: Some political borders have been formalized along natural borders formed by rivers. If a precise line is desired, it is often drawn along the thalweg, the deepest line along the river.
• Lakes: larger lakes create natural borders.
• Forests: denser jungles or forests can create strong natural borders.
• Mountain ranges: Many nations have their political borders defined along mountain ranges, often along a drainage divide.

Throughout history, technological advances have reduced the costs of transport and communication across the natural borders. That has reduced the significance of natural borders over time. As a result, political borders that have been formalized more recently, such as those in Africa or Americas, typically conform less to natural borders{{Citation needed|date=January 2023}} than very old borders, such as those in Europe or Asia, do.

A landscape border is a mixture of political and natural borders. One example is the defensive forest created by China's Song dynasty in the eleventh century.{{Cite journal |last=Chen |first=Yuan Julian |title=Frontier, Fortification, and Forestation: Defensive Woodland on the Song–Liao Border in the Long Eleventh Century |date=July 2018 |journal=Journal of Chinese History |language=en |volume=2 |issue=2 |pages=313–334 |doi=10.1017/jch.2018.7 |issn=2059-1632 |doi-access=free}} Such a border is political in the sense that it is human-demarcated, usually through a treaty. However, a landscape border is not demarcated by fences and walls but instead landscape features such as forests, mountains, and water bodies. It is different from a natural border, however, in the sense that the border landscape is not natural but human-engineered. Such a landscape usually differs from the borderland's natural geography and its building requires tremendous human labour and financial investment.

Geometric boundaries{{citation needed|date=November 2017}} are formed by straight lines (such as lines of latitude or longitude), or occasionally arcs (Pennsylvania/Delaware), regardless of the physical and cultural features of the area. Such political boundaries are often found around the states that developed out of colonial holdings, such as in North America,{{Cite web |last=Winterhalter |first=Elizabeth |date=2018-10-20 |title=Why Are U.S. Borders Straight Lines? |url=https://daily.jstor.org/why-are-u-s-borders-straight-lines/ |access-date=2023-01-05 |website=JSTOR Daily |language=en-US}} Africa{{Citation needed|date=January 2023}} and the Middle East. The Canada–United States border follows the 49th parallel for roughly {{convert|2175|mi|km}} from Lake of the Woods (Ontario and Minnesota) west to the Pacific Ocean.

A generalization of the idea of geometric borders is the idea of fiat boundaries by which is meant any sort of boundary that does not track an underlying bona fide physical discontinuity (fiat, Latin for "let it be done", a decision). Fiat boundaries are typically the product of human demarcation, such as in demarcating electoral districts or postal districts.{{cite book |last=Smith |first=Barry |date=1995 |chapter-url=http://ontology.buffalo.edu/smith/articles/drawing.html |chapter=On Drawing Lines on a Map |editor1-first=A. U. |editor1-last=Frank |editor2-first=W. |editor2-last=Kuhn |editor3-first=D. M. |editor3-last=Mark |title=Spatial Information Theory. Proceedings of COSIT 1995 |location=Berlin/Heidelberg/Vienna/New York/London/Tokyo |publisher=Springer Verlag |pages=475–484 |access-date=2017-01-03 |archive-date=2019-02-09 |archive-url=https://web.archive.org/web/20190209154942/http://ontology.buffalo.edu/smith/articles/drawing.html |url-status=live }}

File:Greatwall-SA3.jpg was to stop people and militaries from crossing the northern border of China. Today it is a relic border.]]

A relic border is a former boundary, which may no longer be a legal boundary at all. However, the former presence of the boundary can still be seen in the landscape. For instance, the boundary between East and West Germany is no longer an international boundary, but it can still be seen because of historical markers on the landscape; it remains a cultural and economic demarcation in Germany. Other examples include the Demilitarized Zone between North and South Vietnam (defunct since 1975) and the border between North and South Yemen (defunct since 1990). Occasionally a relic border is reconstituted in some form, for example the border between British Somaliland and Italian Somaliland ceased to exist when the two colonies merged to form the independent state of Somalia in 1960, however when the former British Somaliland declared independence in 1991 it claimed the former British-Italian line as its eastern border.{{cite web |title=The Constitution of the Republic of Somaliland |publisher=Government of Somaliland |date=1 May 2001 |url=http://www.chr.up.ac.za/undp/domestic/docs/c_Somaliland.pdf |access-date=2 February 2010 |archive-url=https://web.archive.org/web/20120227110751/http://www.chr.up.ac.za/undp/domestic/docs/c_Somaliland.pdf |archive-date=27 February 2012 |url-status=dead}}

A line of control (LoC) refers to a militarized buffer border between two or more nations that has yet to achieve permanent border status. LoC borders are typically under military control and are not recognized as an official international border. Formally known as a cease-fire line, an LoC was first created with the Simla Agreement between India and Pakistan.{{Cite news |url=https://www.stimson.org/simla-agreement |title=Simla Agreement |work=Stimson Center |access-date=24 July 2018 |language=en |archive-date=15 February 2019 |archive-url=https://web.archive.org/web/20190215140447/https://www.stimson.org/simla-agreement |url-status=live }} Similar to a cease-fire line, an LoC is typically the result of war, military stalemates and unresolved land ownership conflict.{{Cite news |url=http://news.bbc.co.uk/2/shared/spl/hi/south_asia/03/kashmir_future/html/ |title=The Future of Kashmir |work=BBC News |access-date=24 July 2018 |archive-date=19 March 2017 |archive-url=https://web.archive.org/web/20170319084333/http://news.bbc.co.uk/2/shared/spl/hi/south_asia/03/kashmir_future/html/ |url-status=live }}

{{Main|Maritime boundary}}

A maritime border is a division enclosing an area in the ocean where a nation has exclusive rights over the mineral and biological resources,{{Cite web |website=VLIZ Maritime Boundaries Geodatabase |url=http://www.vliz.be/vmdcdata/marbound/info.php |title=General info |access-date=19 November 2010 |archive-date=15 June 2012 |archive-url=https://web.archive.org/web/20120615104053/http://www.vliz.be/vmdcdata/marbound/info.php |url-status=live }} encompassing maritime features, limits and zones.{{cite web |website=Geoscience Australia |url=http://www.ga.gov.au/marine/jurisdiction/definitions.jsp |title=Maritime definitions |url-status= |access-date=19 November 2010}}{{dead link|date=September 2023}} Maritime borders represent the jurisdictional borders of a maritime nation{{cite web |website=United States Department of State |url=http://www.state.gov/g/oes/ocns/opa/convention/c28187.htm |title=Maritime boundaries |archive-url=https://web.archive.org/web/20090419184424/http://www.state.gov/g/oes/ocns/opa/convention/c28187.htm |archive-date=19 April 2009 |access-date=19 November 2010}} and are recognized by the United Nations Convention on the Law of the Sea.

Maritime borders exist in the context of territorial waters, contiguous zones, and exclusive economic zones; however, the terminology does not encompass lake or river boundaries, which are considered within the context of land boundaries.

Some maritime borders have remained indeterminate despite efforts to clarify them. This is explained by an array of factors, some of which illustrate regional problems.{{cite book |last=Valencia |first=Mark J. |date=2001 |title=Maritime Regime Building: Lessons Learned and Their Relevance for Northeast Asia |pages=149–166 |url={{Google books|ZhXN8ILQCnIC|page=149|plainurl=yes}}}}

Airspace is the atmosphere located within a country's controlled international and maritime borders. All sovereign countries hold the right to regulate and protect air space under the international law of Air sovereignty.{{Cite encyclopedia |url=https://www.britannica.com/topic/air-law |title=Air law |encyclopedia=Encyclopedia Britannica |access-date=26 July 2018 |language=en |archive-date=12 April 2019 |archive-url=https://web.archive.org/web/20190412004947/https://www.britannica.com/topic/air-law |url-status=live }} The horizontal boundaries of airspace are similar to the policies of "high seas" in maritime law. Airspace extends 12 nautical miles from the coast of a country and it holds responsibility for protecting its own airspace unless under NATO peacetime protection.{{Cite web |url=https://ac.nato.int/page5931922/-nato-air-policing |website=Allied Air Command |title=NATO Air Policing |publisher=NATO |access-date=28 February 2019 |archive-date=26 March 2019 |archive-url=https://web.archive.org/web/20190326090020/https://ac.nato.int/page5931922/-nato-air-policing |url-status=live }} With international agreement a country can assume the responsibility of protecting or controlling the atmosphere over International Airspaces such as the Pacific Ocean. The vertical boundaries of airspace are not officially set or regulated internationally. However, there is a general agreement of vertical airspace ending at the point of the Kármán line.{{Cite thesis |last=Reinhardt |first=Dean |date=June 2005 |title=The Vertical Limit of State Sovereignty |url=http://apps.dtic.mil/dtic/tr/fulltext/u2/a436627.pdf |archive-url=https://archive.today/20181115132014/http://www.dtic.mil/dtic/tr/fulltext/u2/a436627.pdf |url-status=live |archive-date=15 November 2018 |type=Master of Laws |publisher=McGill University |pages=3}} The Kármán line is a peak point at the altitude of 62 mi (100 km) above the Earth's surface, setting a boundary between the atmosphere (airspace) and outer space (which is governed by space law).{{Cite web |url=http://www.inesap.org/bulletin20/bul20art08.htm |archive-url=https://web.archive.org/web/20080515202422/http://www.inesap.org/bulletin20/bul20art08.htm |url-status=dead |archive-date=15 May 2008 |title=Bulletin 20 – Space Weapons Ban: Thoughts on a New Treaty |date=15 May 2008 |access-date=26 July 2018}}

{{Main|Frontier|Frontier thesis|Terra nullius}}

The frontier is a border that is open-ended to one side, identifying an expanding borderland to one side.

This type of border can be fairly abstract and has been identified as a particular state of mind{{cite journal |last=Mura |first=Andrea |year=2016 |title=National Finitude and the Paranoid Style of the One |journal=Contemporary Political Theory |volume=15 |pages=58–79 |doi=10.1057/cpt.2015.23 |s2cid=53724373 |url=https://research.gold.ac.uk/19373/1/Mura%20-%20National%20Finitude%20and%20the%20Paranoid%20Style%20of%20the%20One.pdf |access-date=2020-09-29 |archive-date=2020-09-30 |archive-url=https://web.archive.org/web/20200930021046/http://research.gold.ac.uk/19373/1/Mura%20-%20National%20Finitude%20and%20the%20Paranoid%20Style%20of%20the%20One.pdf |url-status=live }} for human activity. As such frontiers have been applied to borderlands identifying and claiming them as terra nullius, such as Marie Byrd Land in West Antarctica, the only territory in Antarctica unclaimed by any sovereign nation.{{Cite web |title=Making claims |url=https://discoveringantarctica.org.uk/how-is-antarctica-governed/the-antarctic-treaty/making-claims/ |access-date=2023-11-29 |website=Discovering Antarctica |language=en-GB}}

{{Main|Border control}}

In places where smuggling, migration, and infiltration are a problem, many countries fortify borders with fences and barriers, and institute formal border control procedures. These can extend inland, as in the United States where the U.S. Customs and Border Protection service has jurisdiction to operate up to 100 miles from any land or sea boundary.{{cite web |url=https://www.aclu.org/other/constitution-100-mile-border-zone |title=The Constitution in the 100-Mile Border Zone |website=American Civil Liberties Union |access-date=2018-05-03 |archive-date=2020-06-04 |archive-url=https://web.archive.org/web/20200604063515/https://www.aclu.org/other/constitution-100-mile-border-zone |url-status=live }} On the other hand, some borders are merely signposted. This is common in countries within the European Schengen Area and on rural sections of the Canada–United States border. Borders may even be completely unmarked, typically in remote or forested regions; such borders are often described as "porous". Migration within territorial borders, and outside of them, represented an old and established pattern of movement in African countries, in seeking work and food, and to maintain ties with kin who had moved across the previously porous borders of their homelands. When the colonial frontiers were drawn, Western countries attempted to obtain a monopoly on the recruitment of labor in many African countries, which altered the practical and institutional context in which the old migration patterns had been followed, and some might argue, are still followed today. The frontiers were particularly porous for the physical movement of migrants, and people living in borderlands easily maintained transnational cultural and social networks.

File:Ambassador Bridge crossing.jpg into Canada from the US]]

Regulated borders have varying degrees of control on the movement of persons and trade between nations and jurisdictions. Most industrialized nations have regulations on entry and require one or more of the following procedures: visa check, passport check or customs checks.{{Cite web |url=http://www.siue.edu/GEOGRAPHY/ONLINE/Vogeler/ControlledBorders.htm |title=Types of International Borders along the U.S.–Mexico Border |first=Ingolf |last=Vogeler |website=www.siue.edu |access-date=28 July 2018 |archive-date=7 January 2019 |archive-url=https://web.archive.org/web/20190107141432/http://www.siue.edu/GEOGRAPHY/ONLINE/Vogeler/ControlledBorders.htm |url-status=live }} Most regulated borders have regulations on immigration, types of wildlife and plants, and illegal objects such as drugs or weapons. Overall border regulations are placed by national and local governments and can vary depending on nation and current political or economic conditions. Some of the most regulated borders in the world include: Australia, the United States, Israel, Canada, the United Kingdom, and the United Arab Emirates.{{Cite news |url=http://www.traveller.com.au/border-force-the-worlds-toughest-customs-and-immigration-gt0zi3 |title=Border Force: The world's toughest customs and immigration |last=Groundwater |first=Ben |date=30 November 2016 |work=Traveller |access-date=28 July 2018 |language=en-US |archive-date=27 February 2019 |archive-url=https://web.archive.org/web/20190227064639/http://www.traveller.com.au/border-force-the-worlds-toughest-customs-and-immigration-gt0zi3 |url-status=live }} These nations have government-controlled border agencies and organizations that enforce border regulation policies on and within their borders.

File:Wagah border ceremony2.jpg

An open border is the deregulation and or lack of regulation on the movement of persons between nations and jurisdictions. This definition does not apply to trade or movement between privately owned land areas.{{Cite web |url=http://dictionary.cambridge.org/us/dictionary/english/open-border |archive-url=https://web.archive.org/web/20160503193452/http://dictionary.cambridge.org/us/dictionary/english/open-border |url-status=dead |archive-date=3 May 2016 |title=open border Definition in the Cambridge English Dictionary |date=3 May 2016 |access-date=27 July 2018}} Most nations have open borders for travel within their nation of travel, though more authoritarian states may limit the freedom of internal movement of its citizens, as for example in the former USSR. However, only a handful of nations have deregulated open borders with other nations, an example of this being European countries under the Schengen Agreement or the open Belarus-Russia border.{{Cite web |url=https://ec.europa.eu/home-affairs/what-we-do/policies/borders-and-visas/schengen_en |title=Schengen Area - Migration and Home Affairs – European Commission |last=Anonymous |date=6 December 2016 |website=Migration and Home Affairs – European Commission |language=en |access-date=27 July 2018 |archive-date=12 August 2021 |archive-url=https://web.archive.org/web/20210812074419/https://ec.europa.eu/home-affairs/what-we-do/policies/borders-and-visas/schengen_en |url-status=live }} Open borders used to be very common amongst all nations, however this became less common after the First World War, which led to the regulation of open borders, making them less common and no longer feasible for most industrialized nations.{{cite web |url=http://www.populationenvironmentresearch.org/papers/Colemanmigration.pdf |title=International Union for the Scientific Study of Population : XXIV General Population Conference, Salvador da Bahia, Brazil : Plenary Debate no 4 |archive-url=https://web.archive.org/web/20140801080227/http://www.populationenvironmentresearch.org/papers/Colemanmigration.pdf |archive-date=1 August 2014 |website=Population Environment Research |date=24 August 2001 |access-date=26 July 2018}} An example of Open orders include the Schengen Area where 29 European nations mutually abolished their border control.{{Cite web |title=Schengen Area – European Commission |url=https://home-affairs.ec.europa.eu/policies/schengen-borders-and-visa/schengen-area_en |access-date=2024-10-23 |website=home-affairs.ec.europa.eu |language=en}}

{{See also|No man's land|Demarcation line|Terra nullius|Buffer zone}}

A demilitarized zone (DMZ) is a border separating two or more nations, groups or militaries that have agreed to prohibit the use of military activity or force within the border's bounds. A DMZ can act as a war boundary, ceasefire line, wildlife preserve, or a de facto international border. An example of a demilitarized international border is the 38th parallel between North and South Korea.{{Cite encyclopedia |url=https://www.britannica.com/place/demilitarized-zone-Korean-peninsula |title=demilitarized zone (DMZ) {{!}} Definition, Facts, & Pictures |encyclopedia=Encyclopedia Britannica |access-date=26 July 2018 |language=en |archive-date=20 February 2019 |archive-url=https://web.archive.org/web/20190220221433/https://www.britannica.com/place/demilitarized-zone-Korean-peninsula |url-status=live }} Other notable DMZ zones include Antarctica and outer space (consisting of all space 100 miles away from the earth's surface), both are preserved for world research and exploration.{{Cite encyclopedia |url=https://www.britannica.com/event/Antarctic-Treaty |title=Antarctic Treaty {{!}} 1959 |encyclopedia=Encyclopedia Britannica |access-date=26 July 2018 |language=en |archive-date=26 July 2018 |archive-url=https://web.archive.org/web/20180726072601/https://www.britannica.com/event/Antarctic-Treaty |url-status=live }}{{Cite encyclopedia |url=https://www.britannica.com/event/Outer-Space-Treaty |title=Outer Space Treaty {{!}} 1967 |encyclopedia=Encyclopedia Britannica |access-date=26 July 2018 |language=en |archive-date=23 February 2019 |archive-url=https://web.archive.org/web/20190223195506/https://www.britannica.com/event/Outer-Space-Treaty |url-status=live }} The prohibition of control by nations can make a DMZ unexposed to human influence and thus developed into a natural border or wildlife preserve, such as on the Korean Demilitarized Zone, the Vietnamese Demilitarized Zone, and the Green Line in Cyprus.{{Cite news |url=https://www.nytimes.com/2007/06/07/world/asia/07iht-dmz.1.6036533.html |title=Wildlife preserve planned for Korean demilitarized zone |access-date=26 July 2018 |work=The New York Times |date=7 June 2007 |language=en |archive-date=26 July 2018 |archive-url=https://web.archive.org/web/20180726072312/https://www.nytimes.com/2007/06/07/world/asia/07iht-dmz.1.6036533.html |url-status=live }}{{Cite news |url=http://www.neontommy.com/2009/11/military-zones-mean-boon-for-b |title=Military Zones Mean Boon For Biodiversity |last=Ahearn |first=Ashley |access-date=26 July 2018 |language=en |archive-url=https://web.archive.org/web/20180726103559/http://www.neontommy.com/2009/11/military-zones-mean-boon-for-b |archive-date=26 July 2018 |url-status=dead}}

{{Main|Border trade}}

{{See also|Customs|Cross-border trade|Free-trade zone}}

File:Tijuana border San Diego.jpg–Tijuana.]]

File:Borderbeachtj.jpg

Borders undermine economic activity and development by reducing trade activity.{{Cite journal |last1=Anderson |first1=James E. |last2=van Wincoop |first2=Eric |date=2003 |title=Gravity with Gravitas: A Solution to the Border Puzzle |url=https://www.aeaweb.org/articles?id=10.1257/000282803321455214 |journal=American Economic Review |language=en |volume=93 |issue=1 |pages=170–192 |doi=10.1257/000282803321455214 |s2cid=7277314 |issn=0002-8282 |hdl=10532/3989 |hdl-access=free |access-date=2022-07-26 |archive-date=2022-07-26 |archive-url=https://web.archive.org/web/20220726174430/https://www.aeaweb.org/articles?id=10.1257/000282803321455214 |url-status=live }}{{Cite journal |last=Nagy |first=Dávid Krisztián |date=2022 |title=Trade and Urbanization: Evidence from Hungary |journal=American Economic Journal: Microeconomics |language=en |volume=14 |issue=3 |pages=733–790 |doi=10.1257/mic.20180270 |s2cid=239873111 |issn=1945-7669|doi-access=free }}{{Cite journal |last1=Brakman |first1=Steven |last2=Garretsen |first2=Harry |last3=van Marrewijk |first3=Charles |last4=Oumer |first4=Abdella |date=2012 |title=The Border Population Effects of EU Integration |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1467-9787.2011.00752.x |journal=Journal of Regional Science |language=en |volume=52 |issue=1 |pages=40–59 |doi=10.1111/j.1467-9787.2011.00752.x |bibcode=2012JRegS..52...40B |s2cid=55067930 |hdl=10.1111/j.1467-9787.2011.00752.x |hdl-access=free |access-date=2022-07-26 |archive-date=2022-07-26 |archive-url=https://web.archive.org/web/20220726174429/https://onlinelibrary.wiley.com/doi/10.1111/j.1467-9787.2011.00752.x |url-status=live }}

The presence of borders often fosters certain economic features or anomalies. Wherever two jurisdictions come into contact, special economic opportunities arise for border trade. Smuggling provides a classic case; contrariwise, a border region may flourish on the provision of excise or of import–export services — legal or quasi-legal, corrupt or legitimate. Different regulations on either side of a border may encourage services to position themselves at or near that border: thus the provision of pornography, of prostitution, of alcohol, fireworks, and/or of narcotics may cluster around borders, city limits, county lines, ports and airports. In a more planned and official context, Special Economic Zones (SEZs) often tend to cluster near borders or ports.

Even if the goods are not perceived to be undesirable, states will still seek to document and regulate the cross-border trade in order to collect tariffs and benefit from foreign currency exchange revenues.{{cite web |last=Pavanello |first=Sara |date=2010 |url=http://www.odi.org.uk/resources/details.asp?id=4997&title=working-across-borders-harnessing-potential-cross-border-activities-improve-livelihood-security-horn-africa-drylands |title=Working across borders – Harnessing the potential of cross-border activities to improve livelihood security in the Horn of Africa drylands |archive-url=https://web.archive.org/web/20101112224025/http://www.odi.org.uk/resources/details.asp?id=4997&title=working-across-borders-harnessing-potential-cross-border-activities-improve-livelihood-security-horn-africa-drylands |archive-date=12 November 2010 |location=London |website=Overseas Development Institute}} Thus, there is the concept unofficial trade in goods otherwise legal; for example, the cross-border trade in livestock by pastoralists in the Horn of Africa. Ethiopia sells an estimated $250 to $300 million of livestock to Somalia, Kenya and Djibouti every year unofficially, over 100 times the official estimate.

Human economic traffic across borders (apart from kidnapping) may involve mass commuting between workplaces and residential settlements. The removal of internal barriers to commerce, as in France after the French Revolution or in Europe since the 1940s, de-emphasizes border-based economic activity and fosters free trade. Euroregions are similar official structures built around commuting across boundary.

{{Main|National boundary delimitation}}

{{See also|Territorial integrity|Passport|Immigration law|Travel visa|}}

File:IsraelCVFRchart-BorderNorth copy.jpg and Lebanon in Mount Hermon region.

The Blue Line between Israel and Lebanon—marked by black asterisk.

Disengagement Israeli front line with Syria (1974)—marked by blue asterisk.

Disengagement Syrian front line with Israel (1974)—marked by red asterisk.

]]

Political borders have a variety of meanings for those whom they affect. Many borders in the world have checkpoints where border control agents inspect persons and/or goods crossing the boundary.

Some borders require presentation of legal paperwork like passports and visas, or other identity documents, for persons to cross borders. To stay or work within a country's borders aliens (foreign persons) may need special immigration documents or permits; but possession of such documents does not guarantee that the person should be allowed to cross the border.

Moving goods across a border often requires the payment of excise tax, often collected by customs officials. Animals (and occasionally humans) moving across borders may need to go into quarantine to prevent the spread of exotic infectious diseases. Most countries prohibit carrying illegal drugs or endangered animals across their borders. Moving goods, animals, or people illegally across a border, without declaring them or seeking permission, or deliberately evading official inspection, constitutes smuggling. Controls on car liability insurance validity and other formalities may also take place.

File:CBP female officers going aboard a ship.jpg

A border may have been:

• Agreed by the countries on both sides
• Imposed by the country on one side
• Imposed by third parties, e.g. an international conference
• Inherited from a former state, colonial power or aristocratic territory
• Inherited from a former internal border, such as within the former Soviet Union
• Never formally defined.

In addition, a border may be a de facto military ceasefire line.

In much of Europe, controls on persons were abolished by the 1985 Schengen Agreement and subsequent European Union legislation. Since the Treaty of Amsterdam, the competence to pass laws on crossing internal and external borders within the European Union and the associated Schengen Area states (Iceland, Norway, Switzerland, and Liechtenstein) lies exclusively within the jurisdiction of the European Union, except where states have used a specific right to opt out (United Kingdom and Ireland, which maintain the Common Travel Area amongst themselves).

The United States has notably increased measures taken in border control on the Canada–United States border and the United States–Mexico border during its War on Terrorism (See Shantz 2010). One American writer has said that the {{convert|3,600|km|mi|abbr=on}} US-Mexico border is probably "the world's longest boundary between a First World and Third World country".{{cite news |last=Murphy |first=Cullen |title=Roman Empire: gold standard of immigration |work=Los Angeles Times |date=16 June 1907 |access-date=20 June 2007 |url=http://www.latimes.com/news/opinion/la-oe-murphy16jun16,0,7065340.story?coll=la-opinion-rightrail |archive-date=22 August 2007 |archive-url=https://web.archive.org/web/20070822101808/http://www.latimes.com/news/opinion/la-oe-murphy16jun16,0,7065340.story?coll=la-opinion-rightrail |url-status=live }}{{Update inline|date=October 2019}}

File:Valico Ponte Tresa.JPG]]

Historic borders such as the Great Wall of China, the Maginot Line, and Hadrian's Wall have played a great many roles and been marked in different ways. While the stone walls, the Great Wall of China and the Roman Hadrian's Wall in Britain had military functions, the entirety of the Roman borders were very porous, which encouraged Roman economic activity with neighbors. On the other hand, a border like the Maginot Line was entirely military and was meant to prevent any access in what was to be World War II to France by its neighbor, Germany; Germany ended up going around the Maginot Line through Belgium just as it had done in World War I.

{{Main|Border conflict}}Border conflicts are disputes between territories that occur at the borders separating said territories. They occur when one party constructs identities or interests related to the border which are incompatible with the other party's identities and interests.{{Cite journal |last=Diez |first=Thomas |date=Summer 2006 |title=The European Union and Border Conflicts: The Transformative Power of Integration |url=https://www.jstor.org/stable/3877820 |journal=International Organization |volume=60 |issue=3 |pages=563–593 |doi=10.1017/S0020818306060218 |doi-broken-date=7 December 2024 |jstor=3877820 |access-date=2024-11-24 |archive-date=2024-04-03 |archive-url=https://web.archive.org/web/20240403072055/https://www.jstor.org/stable/3877820 |url-status=live }} Border conflicts or the potential of such are the reason why many borders feature fortifications and zoning like no man's lands, demilitarized zones, demarcation lines and buffer zones. Examples of border conflicts include skirmishes and wars, such as the 38th Parallel (between North and South Korea), Western Sahara conflict, and Kashmir region conflicts between India and Pakistan.

A border conflict can occur due to several reasons. Most commonly, territorial disputes can result in border conflicts, as it is the case with the Kashmir conflict.{{Cite news |date=2002-06-02 |title=China and the Kashmir crisis |url=http://news.bbc.co.uk/1/hi/world/south_asia/2020788.stm |access-date=2024-11-24 |language=en-GB |archive-date=2009-01-12 |archive-url=https://web.archive.org/web/20090112015242/http://news.bbc.co.uk/1/hi/world/south_asia/2020788.stm |url-status=live }}

{{Main|Boundary marker|Border barrier|Separation barrier}}

{{See also|Border outpost|Observation post|Buffer zone|Defensive wall|Barricade|Wall|Fence|Landmark}}

File:Anarchist anti deporation protest.jpg protest against borders and deportations in Minneapolis, United States]]

While many borders are based on specific natural landscape features, some borders have additional man-made infrastructure. Fencing is used for security reasons, mainly to prevent unauthorised activity between the borders, including the travelling and transport of humans and goods.{{Cite web |title=Border Wall System - Frequently Asked Questions {{!}} U.S. Customs and Border Protection |url=https://www.cbp.gov/border-security/border-wall/border-wall-system-frequently-asked-questions? |access-date=2025-02-08 |website=www.cbp.gov |language=en}}{{Cite web |date=5 June 2024 |title=Australia's biosecurity and border controls |url=https://www.smartraveller.gov.au/while-youre-away/biosecurity-border |access-date=8 February 2025 |website=SmartTraveller}} In a state of increased tension, borders may also be heavily fortified, with defensive infrastructure being built.{{Cite web |date=2007-10-12 |title=" The Berlin wall : History of Berlin Wall : Facts " |url=http://die-berliner-mauer.de/en/fakten.html |access-date=2025-02-08 |website=die-berliner-mauer.de |archive-url=https://web.archive.org/web/20071012011801/http://die-berliner-mauer.de/en/fakten.html |archive-date=2007-10-12}} Crossings may be built into a border to allow for regulated crossing into such territory.{{Cite web |title=Australian Border Force Website |url=https://www.abf.gov.au/entering-and-leaving-australia/crossing-the-border/overview |archive-url=http://web.archive.org/web/20241204171728/https://www.abf.gov.au/entering-and-leaving-australia/crossing-the-border/overview |archive-date=2024-12-04 |access-date=2025-02-08 |website=Australian Border Force Website |language=en-AU}}

{{Main|Border checkpoint|Port of entry}}

{{See also|Border town|Trading post|Port|International Airport|Custom house}}

File:Nuijamaa border crossing 2017 03 (cropped).jpg side of the Russian border at the Nuijamaa Border Crossing Point in Nuijamaa, Lappeenranta, Finland]]

Even the most fortified borders reserve specific places to allow crossing. The many forms of borders have different ways of enabling and controlling passage.

{{Main|Border control|International migration|Migration (ecology)|Seed dispersal|Pollution}}

Borders can have a significant impact on and function for movement. It can enable and stop movement, across as well as along borders.

The permeability of borders depends on its construction, availability of crossings, regulation and types or scope of activity. The permeability can vary, borders can be barriers for humans, but also for animal migration or types of pollution.

{{Main|Cross-border cooperation|Third place|Hybridity|Third Space Theory}}

{{See also|Internationalism (politics)|Federalism|Sister City|Community centre|Free-trade zone|Refugee camp|Freedoms of the air|Dependency theory|Scale (analytical tool)}}

Borders facilitate or block hybrids like border overlap and cooperation beyond mere encounter and exchange.

{{Main|Cross-border region}}

Macro-regional integration initiatives, such as the European Union and NAFTA, have spurred the establishment of cross-border regions. These are initiatives driven by local or regional authorities, aimed at dealing with local border-transcending problems such as transport and environmental degradation.{{cite journal |last=Perkmann |first=M. |title=Building governance institutions across European borders |journal=Regional Studies |date=1999 |volume=33 |issue=7 |pages=657–667 |doi=10.1080/00343409950078693 |bibcode=1999RegSt..33..657P |hdl=10044/1/1343 |s2cid=34665896 |url=http://hdl.handle.net/10044/1/1343|hdl-access=free }} Many cross-border regions are also active in encouraging intercultural communication and dialogue as well as cross-border economic development strategies.
In Europe, the European Union provides financial support to cross-border regions via its Interreg programme. The Council of Europe has issued the Outline Convention on Transfrontier Co-operation, providing a legal framework for cross-border co-operation even though it is in practice rarely used by Euroregions.

There has been a renaissance in the study of borders starting with the end of the 1990s, partially from the creation of a counter-narrative to the discourse about the world becoming a borderless and deterritorialized place, which has accompanied theories about globalization.{{cite journal |first1=D. |last1=Newman |first2=A. |last2=Paasi |title=Fences and neighbours in the post-modern world: boundary narratives in political geography |journal=Progress in Human Geography |volume=22 |number=2 |pages=186–207 |date=1998|doi=10.1191/030913298666039113 |s2cid=143392991 }}{{cite journal |first1=D. |last1=Newman |title=The lines that continue to separate us: Borders in our borderless world |journal=Progress in Human Geography |volume=30 |number=2 |pages=143–161 |date=2006|doi=10.1191/0309132506ph599xx |s2cid=143640667 }} Examples of recent initiatives are the Border Regions in Transition network of scholars,{{cite web |url=http://publicadmin.uvic.ca/brit_ix/index.htm |title=Border Regions in Transition IX Conference, North American and European Border Regions in Comparative Perspective: Markets, States and Border Communities |date=12–15 January 2008 |location=Victoria, BC Canada and Bellingham, WA United States}} the International Boundaries Research Unit at the University of Durham,{{cite web |url=http://www.dur.ac.uk/ibru/ |title=International Boundaries Research Unit |website=University of Durham |access-date=2008-09-24 |archive-date=2009-10-18 |archive-url=https://web.archive.org/web/20091018082015/http://www.dur.ac.uk/ibru/ |url-status=live }} the Association for Borderlands Studies based in North America,{{cite web |url=http://www.absborderlands.org/ |title=Association for Borderland Studies |website=Association for Borderland Studies |access-date=2008-09-24 |archive-date=2011-04-30 |archive-url=https://web.archive.org/web/20110430053814/http://www.absborderlands.org/2JBS.html |url-status=live }} the African Borderlands Research Network{{cite web |url=http://www.aborne.org/ |title=ABORNE |website=ABORNE |archive-url=https://web.archive.org/web/20190804155830/http://www.aborne.org/ |archive-date=4 August 2019}} and the founding of smaller border research centres at Nijmegen{{cite web |url=http://www.ru.nl/ncbr/ |title=Nijmegen Centre for Border Research |website=Radboud Universiteit |access-date=2008-09-24 |archive-date=2013-08-09 |archive-url=https://web.archive.org/web/20130809082538/http://www.ru.nl/ncbr/ |url-status=dead }} and Queen's University Belfast.{{cite web|url=http://www.qub.ac.uk/cibr/ |title=Centre for International Borders Research (CIBR) |website=Queen's University Belfast}}

Border art is a contemporary art practice rooted in the socio-political experience(s), such as of those on the U.S.-Mexico borderlands, or frontera. Since its conception in the mid-1980s, this artistic practice has assisted in the development of questions surrounding homeland, borders, surveillance, identity, race, ethnicity, and national origin(s).

Border art as a conceptual artistic practice, however, opens up the possibility for artists to explore similar concerns of identity and national origin(s) but whose location is not specific to the U.S-Mexico border. A border can be a division, dividing groups of people and families. Borders can include but are not limited to language, culture, social and economic class, religion, and national identity. In addition to a division, a border can also conceive a borderland area that can create a cohesive community separate from the mainstream cultures and identities portrayed in the communities away from the borders, such as the Tijuana-San Diego border between Mexico and the United States.

Border art can be defined as an art that is created in reference to any number of physical or imagined boundaries. This art can but is not limited to social, political, physical, emotional and/or nationalist issues. Border art is not confined to one particular medium. Border art/artists often address the forced politicization of human bodies and physical land and the arbitrary, yet incredibly harmful, separations that are created by these borders and boundaries. These artists are often "border crossers" themselves. They may cross borders of traditional art-making (through performance, video, or a combination of mediums). They may at once be artists and activists, existing in multiple social roles at once. Many border artists defy easy classifications in their artistic practice and work.

{{Div col|colwidth=25em}}

• Border barrier
• Border control
• Border irregularities of the United States
• Boundaries between the continents of Earth
• Boundary delimitation
• Enclave and exclave
• Illegal entry
• List of border conflicts
• List of bordering countries with greatest relative differences in GDP (PPP) per capita
• List of countries and territories by land borders
• List of countries by land and maritime borders
• List of countries that border only one other country
• List of divided islands
• List of international river borders
• List of land borders with dates of establishment
• List of national border changes from 1815 to 1914
• List of national border changes (1914–present)
• List of territorial disputes
• Maritime boundary
• Natural frontiers
• Quadripoint
• Tripoint

{{div col end}}

{{reflist}}

• {{Cite web |url=http://www.borderstories.org/ |title=Border Stories |website=Border Stories – A website devoted to stories from both sides of the U.S. Mexico Border}}
• {{cite web |title=Talking Borders |url=http://www.qub.ac.uk/cibr/talkingborders.htm |archive-url=https://web.archive.org/web/20070915193412/http://www.qub.ac.uk/cibr/talkingborders.htm |archive-date=15 September 2007 |website=Queen's University Belfast}}
• [https://web.archive.org/web/20150104154356/http://www.france24.com/en/f24-interview/20141231-interview-bernard-guetta-national-borders-undermined-syria-iraq-mali-ukraine/ The World in 2015: National borders undermined?] 11-min video interview with Bernard Guetta, a columnist for Libération newspaper and France Inter radio. "For [Guetta], one of the main lessons from international relations in 2014 is that national borders are becoming increasingly irrelevant. These borders, drawn by the colonial powers, were and still are entirely artificial. Now, people want borders along national, religious or ethnic lines. Bernard Guetta calls this a "comeback of real history"."
• Baramova, Maria (2010), [http://ieg-ego.eu/en/threads/crossroads/border-regions/maria-baramova-border-theories-in-early-modern-europe?set_language=en&-C= Border Theories in Early Modern Europe], [http://www.ieg-ego.eu/ EGO - European History Online], Mainz: [http://www.ieg-mainz.de/likecms/index.php Institute of European History], retrieved: March 25, 2021 ([http://nbn-resolving.de/urn:nbn:de:0159-2010092137 pdf]).
• {{Cite journal |last1=James |first1=Paul |author-link1=Paul James (academic) |year=2014 |title=Faces of Globalization and the Borders of States: From Asylum Seekers to Citizens |url=https://www.academia.edu/7773440 |journal=Citizenship Studies |volume=18 |issue=2 |pages=208–23 |doi=10.1080/13621025.2014.886440 |s2cid=144816686}}
• {{Cite journal |last=Mura |first=Andrea |year=2016 |title=National Finitude and the Paranoid Style of the One |journal=Contemporary Political Theory |volume=15 |pages=58–79 |doi= 10.1057/cpt.2015.23 |s2cid=53724373 |url=https://research.gold.ac.uk/19373/1/Mura%20-%20National%20Finitude%20and%20the%20Paranoid%20Style%20of%20the%20One.pdf}}
• Said Saddiki, [https://www.openbookpublishers.com/htmlreader/978-1-78374-368-1/main.html World of Walls: The Structure, Roles and Effectiveness of Separation Barriers]. Cambridge, UK: Open Book Publishers, 2017. [https://doi.org/10.11647/OBP.0121 World of Walls: The Structure, Roles and Effectiveness of Separation Barriers]
• Struck, Bernhard, [http://ieg-ego.eu/en/threads/crossroads/border-regions/bernhard-struck-border-regions?set_language=en&-C= Border Regions], [http://www.ieg-ego.eu/ EGO – European History Online], Mainz: [http://www.ieg-mainz.de/likecms/index.php Institute of European History], 2013, retrieved: March 8, 2021 ([https://d-nb.info/1043623418/34 pdf]).

{{Commons-inline}}

{{Wikivoyage|Border crossings}}

{{Wiktionary|border}}

• [https://web.archive.org/web/20080104025114/http://www.grenzen.150m.com/border.htm Collection of pictures of European borders, mainly intra-Schengen borders]
• [https://web.archive.org/web/20080222234042/http://www.culture-routes.lu/php/fo_index.php?lng=en&back=%2Fphp%2Ffo_index.php%3Flng%3Den%26dest%3Dbd_ac_lst&dest=bd_ac_det&id=00002600 Institut Européen des Itinéraires Culturels homepage]
• [https://web.archive.org/web/20170927191600/http://borderireland.info/ Border Ireland – database of activities and publications on cross-border co-operation on the island of Ireland since 1980's]
• [https://phil.uni-greifswald.de/institute/einrichtungen/gk-baltic-borderlands/ Baltic Borderlands Greifswald] {{Webarchive|url=https://web.archive.org/web/20181005153807/https://phil.uni-greifswald.de/institute/einrichtungen/gk-baltic-borderlands/ |date=2018-10-05 }}

{{Types of administrative division}}

{{Authority control}}