What is Mexico–United States border?
[[Image:Us-mexico-border.jpg|thumb|right|350px|The border between the [[United States]] and [[Mexico]] spans four U.S. states, six Mexican states, and has over twenty commercial railroad crossings.]] [[File:Border USA Mexico.jpg|thumb|right|350px|Border at [[Tijuana]] (right) and southern California (left)]] The '''United States–Mexico border''' is the international [[border]] between the [[United States]] and [[Mexico]]. It runs from [[Imperial Beach]], [[California]], and [[Tijuana]], [[Baja California (state)|Baja California]], in the west to [[Matamoros, Tamaulipas|Matamoros]], [[Tamaulipas]], and [[Brownsville, Texas|Brownsville]], [[Texas]], in the east. It covers a variety of [[terrain]]s, ranging from major [[urban]] areas to inhospitable [[desert]]s. From the [[Gulf of Mexico]] it follows the course of the [[Rio Grande|Rio Grande (Río Bravo del Norte)]] to the border crossing at [[El Paso, Texas|El Paso]], [[Texas]], and [[Ciudad Juárez]], [[Chihuahua (state)|Chihuahua]]. Westward from there it crosses vast tracts of the [[Sonoran Desert|Sonoran]] and [[Chihuahuan Desert]]. Then it crosses the [[Colorado River]] [[River delta|Delta]], west to [[San Diego]] and [[Tijuana]] before reaching the [[Pacific Ocean]]. The US-Mexican border is considered an [[open border]].<ref>{{Cite web |url=https://www.pbs.org/newshour/bb/law/jan-june10/immigration2_05-20.html |title=Mexican President's Visit Returns Immigration to the Spotlight &#124; PBS NewsHour &#124; May 20, 2010 &#124; PBS |website=[[PBS]] |access-date=2017-08-31 |archive-date=2014-01-21 |archive-url=https://web.archive.org/web/20140121093522/http://www.pbs.org/newshour/bb/law/jan-june10/immigration2_05-20.html |url-status=dead }}</ref> The border's total length is {{convert|3,169|km|mi|abbr=on}}, according to figures given by the [[International Boundary and Water Commission]].<ref>{{cite web |url=http://www.ibwc.gov/Files/US-Mx_Boundary_Map.pdf |title=United States Section Directive |accessdate=2011-11-11 |archive-date=2018-05-04 |archive-url=htt