By emmelineboutin. Maps. At Thursday, October 10th 2019, 04:52:52 AM.
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 2,020 kilometers (1,260 mi) to its mouth at the Gulf of Mexico. The Rio Grande frequently meanders along the Texas–Mexico border. As a result, the United States 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 United States settled all outstanding boundary disputes and uncertainties related to the Rio Grande (Río Bravo del Norte) border. The region is characterized by deserts, rugged hills, abundant sunshine, and two major rivers—the Colorado and the Rio Grande (Río Bravo del Norte).
The U.S. maintains immigration offices, called pre-clearance facilities, in eight Canadian airports with international air service to the United States (Calgary, Edmonton, Halifax, Montreal, Ottawa, Toronto-Pearson, Vancouver, and Winnipeg). This expedites travel by allowing flights originating in Canada to land at a U.S. airport without being processed as an international arrival. Canada does not maintain equivalent personnel at U.S. airports due to the sheer number of U.S. departure locations with Canada-bound flights and the limited number of flights compared to the number of U.S.-bound flights that depart major Canadian airports.
The Mexico–United States border extends 3,145 kilometers (1,954 mi), in addition to the maritime boundaries of 29 kilometers (18 mi) in the Pacific Ocean and 19 kilometers (12 mi) in the Gulf of Mexico.
The total length of the continental border is 3,145 kilometers (1,954 mi). From the Gulf of Mexico, it follows the course of the Rio Grande (Río Bravo del Norte) to the border crossing at Ciudad Juárez, Chihuahua, and El Paso, Texas. Westward from El Paso–Juárez, it crosses vast tracts of the Chihuahuan and Sonoran deserts to the Colorado River Delta and San Diego–Tijuana, before reaching the Pacific Ocean.
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 United States, while Nuevo León has the shortest. Along the border are 23 U.S. counties and 39 Mexican municipalities.
The Mexico–United States 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 227 kilometers (141 mi) in a straight line towards the confluence of the Colorado River and Gila River. The border continues southwards along the Colorado River for 39 kilometers (24 mi), until it reaches a point 20 miles south of the Gila River confluence. The border then follows a series of lines and parallels totaling 859 kilometers (534 mi). First, it follows a straight line from the Colorado River to the intersection of the 31st parallel north and 111th meridian west. It then proceeds eastwards along the 31st parallel. It then proceeds northwards along a meridian 100 miles west of the point where the Rio Grande crosses 31 degrees 47 minutes north, and then eastwards along that parallel until it meets the Rio Grande.