mountain pass

File:Saddleroute3.JPG is in red.]]

Mountain passes make use of a gap, saddle, col or notch. A topographic saddle is analogous to the mathematical concept of a saddle surface, with a saddle point marking the minimum high point between two valleys and the lowest point along a ridge.{{sfn|Eberhart|2004|page=[https://books.google.com/books?id=wo9wGKk9MVsC&pg=PT236 232]}}{{sfn|Bishop|Shroder|2004|pages=[https://books.google.com/books?id=6TGu7-mwSNYC&pg=PA86 86–87]}} On a topographic map, passes can be identified by contour lines with an hourglass shape, which indicates a low spot between two higher points.{{sfn|Harvey|Simer|1999|page=[https://books.google.com/books?id=BHKUvFAzliYC&pg=PA185 185]}} In the high mountains, a difference of {{convert|2000|meters}} between the summit and the mountain{{clarify|date=February 2024}} is defined as a mountain pass.{{sfn|Bishop|Shroder|2004|page=[https://books.google.com/books?id=6TGu7-mwSNYC&pg=PA103 103]}}

Passes are often found just above the source of a river, constituting a drainage divide. A pass may be very short, consisting of steep slopes to the top of the pass, or a valley many kilometers long, whose highest point might only be identifiable by surveying.

Roads and railways have long been built through passes. Some high and rugged passes may have tunnels bored underneath a nearby mountainside, as with the Eisenhower Tunnel bypassing Loveland Pass in the Rockies, to allow faster traffic flow throughout the year.

The top of a pass is frequently the only flat ground in the area, and may be a high vantage point. In some cases this makes it a preferred site for buildings. If a national border follows the ridge of a mountain range, a pass over the mountains is typically on the border, and there may be a border control or customs station, and possibly a military post. For instance, Argentina and Chile share the world's third-longest international border, {{convert|5300|km|mi}} long, which runs north–south along the Andes mountains and includes 42 mountain passes.

On a road over a pass, it is customary to have a small roadside sign giving the name of the pass and its elevation above mean sea level.

Apart from offering relatively easy travel between valleys, passes also provide a route between two mountain tops with a minimum of descent. As a result, it is common for tracks to meet at a pass; this often makes them convenient routes even when travelling between a summit and the valley floor. Passes traditionally were places for trade routes, communications, cultural exchange, military expeditions etc. A typical example is the Brenner pass in the Alps.

Some mountain passes above the tree line have problems with snow drift in the winter. This might be alleviated by building the road a few meters above the ground, which will make snow blow off the road.

File:The col (6073968059).jpg, England]]

There are many words for pass in the English-speaking world. In the United States, pass is very common in the West, the word gap is common in the southern Appalachians, notch in parts of New England, and saddle in northern Idaho.[http://itouchmap.com/?f=gap&s=ID&a1=&start=255 Map showing "saddle" names in Idaho] The term col, derived from Old French, is also used, particularly in Europe.{{citation needed|date=January 2025}}

In the highest mountain range in the world, the Himalayas, passes are denoted by the suffix "La" in Tibetan, Ladhakhi, and several other regional languages. Examples are the Taglang La at 5,328 m (17,480 ft) on the Leh-Manali highway, and the Sia La at 5,589 m (18,337 ft) in the Eastern Karakoram range.

Scotland has the Gaelic term bealach (anglicised "balloch"), while Wales has the similar bwlch (both being insular Celtic languages).{{cite book |last=Nicolson |first=A. |title=Modern Gaelic: A Basic Grammar |publisher=A. Maclaren |year=1945 |url=https://books.google.com/books?id=oWViAAAAMAAJ |access-date=18 January 2021 |page=28 |quote=Bealach (mountain-pass)}}{{cite book |title=The Geology of Snowdonia – A Collection of Historical Articles on the Physical Features of the Peaks of Snowdonia |publisher=Read Books Limited |location=City |year=2013 |isbn=978-1-4733-9043-0 |url=https://books.google.com/books?id=ITR-CgAAQBAJ&pg=PT45 |access-date=18 January 2021 |page=45 |quote=The word Bwlch is used in Welsh not only to signify a pass or easy route over a ridge, usually a depression between higher ground on either side, but also ...}} In the Lake District of north-west England, the term hause is often used, although the term pass is also common—one distinction is that a pass can refer to a route, as well as the highest part thereof, while a hause is simply that highest part, often flattened somewhat into a high-level plateau.

In Japan they are known as tōge, which means "pass" in Japanese. The word can also refer to narrow, winding roads that can be found in and around mountains and geographically similar areas, or specifically to a style of street racing which may take place on these roads.

There are thousands of named passes around the world, some of which are well-known, such as the Khyber Pass close to the present-day Afghanistan-Pakistan border on the ancient Silk Road, the Great St. Bernard Pass at {{convert|2473|m|ft}} in the Alps, the Chang La at {{convert|5360|m|ft}}, the Khardung La at {{convert|5359|m|ft}} in Ladakh, India and the Palakkad Gap at {{convert|140|m|ft}} in Palakkad, Kerala, India, which is the widest moutain pass in the world.{{cn|date=April 2025}} The roads at Mana Pass at {{convert|5610|m|ft}} and Marsimik La at {{convert|5582|m|ft}}, on and near the China–India border respectively, appear to be world's two highest motorable passes. Khunjerab Pass between Pakistan and China at {{Convert|4693|m|ft}} is also a high-altitude motorable mountain pass. One of the famous but non-motorable mountain passes is Thorong La at {{convert|5416|m|ft}} in Annapurna Conservation Area, Nepal.

Stilfser Joch Ost.jpg|Stelvio Pass in the Alps (Italy)

Agua negra argentina.JPG|Agua Negra Pass between Argentina and Chile.

Bealach na Ba Pano.jpg|The Bealach na Bà linking Applecross in the Scottish North-west Highlands.

Dead Woman's Pass from above.jpg|Dead Woman's Pass on the Inca Trail to Machu Picchu in Peru

Ornak a14.jpg|Iwaniacka Pass in Tatras (near Kominiarski Wierch, Poland).

Zadielska tiesnava.jpg|Zádielska tiesňava Pass in Slovak Karst (Slovakia).

Way to Thorong La.JPG|Trail from Manang to Mustang via Thorong La pass, Nepal.

Darcha Padum Road Below Shinku La Lahaul Oct22 A7C 03533.jpg|Winding road below Shingo La in Himachal Pradesh, India

CrawfordNotchCenter.jpg|Crawford Notch in New Hampshire, U.S.

{{portal|Mountains|Geography}}

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• {{annotated link|List of mountain passes}}
• {{annotated link|Defile (geography)|Defile}}
• {{annotated link|Water gap}}
• {{annotated link|Wind gap}}

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{{reflist|refs=

{{cite web |url=http://www.gendarmeria.gov.ar/pasos.html |title=Principales Pasos Nacionales e Internacionales – Estado de los Pasos Fronterizos |publisher=Gendarmería Nacional Argentina |language=es |access-date=4 March 2010 |archive-url=https://web.archive.org/web/20100328092538/http://www.gendarmeria.gov.ar/pasos.html |archive-date=28 March 2010}}

{{cite web |url=http://www.gendarmeria.gov.ar/pasos/chile.htm |title=Pasos – Chile |publisher=Gendarmería Nacional Argentina |language=es |access-date=4 March 2010 |archive-url=https://web.archive.org/web/20070718053512/http://www.gendarmeria.gov.ar/pasos/chile.htm |archive-date=2007-07-18}}

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• {{cite book |last1=Bishop |first1=Michael P. |last2=Shroder |first2=John F. |title=Geographic Information Science and Mountain Geomorphology |year=2004 |location=Berlin New York |publisher=Springer Publishing |isbn=978-3-540-42640-0 |pages=86–87 |url=https://books.google.com/books?id=6TGu7-mwSNYC&pg=PA86 |access-date=6 November 2010}}
• {{cite book |last=Eberhart |first=Mark E. |author-link=Mark Eberhart|title=Why Things Break: Understanding the World by the Way it Comes Apart |year=2004 |publisher=Random House, Harmony Books |location=New York |isbn=978-1-4000-4883-0 |page=232 |url=https://books.google.com/books?id=wo9wGKk9MVsC&pg=PT236 |access-date=6 November 2010}}
• {{cite book |last1=Harvey |first1=Mark William Thornton |last2=Simer |first2=Peter |title=The National Outdoor Leadership School Wilderness Guide: The Classic Handbook |year=1999 |location=New York|publisher=Simon & Schuster |isbn=978-0-684-85909-5 |page=185 |url=https://books.google.com/books?id=BHKUvFAzliYC&pg=PA185 |access-date=6 November 2010}}
• {{cite book |title=The Geology of Snowdonia – A Collection of Historical Articles on the Physical Features of the Peaks of Snowdonia |publisher=Read Books Limited |location=City |year=2013 |isbn=978-1-4733-9043-0 |url=https://books.google.com/books?id=ITR-CgAAQBAJ&pg=PT45 |access-date=18 January 2021 |page=45 |quote=The word Bwlch is used in Welsh not only to signify a pass or easy route over a ridge, usually a depression between higher ground on either side, but also ...}}

• {{commons category-inline|Mountain passes}}

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Category:Montane ecology

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Category:Slope landforms

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