Which river forms much of the border between the United States and Mexico?

A large part of the border between the United States and Mexico is formed by a single river: the Rio Grande. In Mexico, the same river is known by a different name, the Rio Bravo. For a long stretch of the international boundary, this river is the line that separates the two countries.

The Rio Grande begins far to the north, high in the mountains of Colorado, and flows south and then southeast for a great distance before reaching the sea at the Gulf of Mexico. It is along its lower course that the river acts as the border. It separates the U.S. state of Texas from several Mexican states, before finally emptying into the Gulf.

Using a river as a border brings challenges. Rivers naturally change course over time, and shifts in the Rio Grande have caused boundary disputes between the two countries in the past. The river also faces a modern problem: so much of its water is taken for farms and cities along the way that only a small fraction of its natural flow now reaches the sea. Twin border cities, such as El Paso and Ciudad Juarez, face each other across its banks.

This article was written using information from Wikipedia.