Mexico–United States border

The Mexico–United States border is an international boundary running from Tijuana, Baja California, and Imperial Beach, California, in the west to Matamoros, Tamaulipas, and Brownsville, Texas, in the east. This border, separating Mexico and the United States from each other, traverses a variety of terrains, ranging from major urban areas to uninhabitable deserts. It is the most frequently crossed controlled international boundary in the world, with approximately 350 million legal crossings being made annually.

The total length of the continental border is 3,201 kilometers (1,989 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 that binational conurbation it crosses vast tracts of the Chihuahuan and Sonoran Deserts to the Colorado River Delta, westward to the binational conurbation of San Diego, California, and Tijuana, Baja California, before reaching the Pacific Ocean.

Following the Boundary Treaty of 1970 between the United States and Mexico that settled all then pending boundary disputes and uncertainties related to the Rio Grande (Río Bravo del Norte) border, the international continental border extends 3,145 kilometers (1,954 mi), excluding the maritime boundaries of 29 km (18 mi) in the Pacific Ocean and 19 km (12 mi) in the Gulf of Mexico.

...
Wikipedia