What is the Rio Grande?

The Rio Grande is a river forming about 1,254 miles of the international boundary between the United States (specifically Texas) and Mexico, running from El Paso, Texas to the Gulf of Mexico at Brownsville, Texas, where it empties into the Gulf about 25 miles east of the city. The full length of the river is about 1,896 miles, making it the fourth or fifth longest river in the United States, depending on the measurement. It rises in the San Juan Mountains of southwestern Colorado at an elevation of about 12,000 feet, flows south through the San Luis Valley of southern Colorado and into northern New Mexico, passes through Albuquerque (where it provides much of the city's water), continues south through Las Cruces and into Texas at El Paso, where it begins forming the international boundary.

The river is called the Rio Grande in the United States and the Rio Bravo or Rio Bravo del Norte in Mexico. The boundary along the Rio Grande was established by the Treaty of Guadalupe Hidalgo on February 2, 1848 ending the Mexican-American War. The treaty resolved the dispute over whether the southern boundary of Texas was the Rio Grande or the Nueces River 100 miles to the north, with Mexico relinquishing its claim. Subsequent boundary disputes were settled by treaties of 1884 and 1933, with the Chamizal Convention of 1963 resolving a long standing dispute around El Paso/Ciudad Juarez by physically rerouting a section of the river.

The river is heavily controlled by dams. Elephant Butte Dam in New Mexico, completed in 1916, creates Elephant Butte Reservoir, a major source for irrigation. Caballo Dam in New Mexico and Amistad Dam (1969) and Falcon Dam (1953) on the U.S.-Mexico border further regulate flow. The Rio Grande Compact of 1939 allocates water among Colorado, New Mexico, and Texas. The 1944 U.S.-Mexico Water Treaty allocates Rio Grande water below Fort Quitman, Texas between the two countries.

Despite its great length, the Rio Grande is a relatively small river by volume, and water demand often exceeds available supply. The river often runs dry in stretches between El Paso and Presidio, Texas. Major cities along the river include Albuquerque, Las Cruces, El Paso/Ciudad Juarez (the largest international metropolitan area on the border), Del Rio/Ciudad Acuna, Eagle Pass/Piedras Negras, Laredo/Nuevo Laredo, McAllen/Reynosa, and Brownsville/Matamoros. The Rio Grande Valley along the lower river is a major agricultural area producing citrus, vegetables, and cotton.

The river has cultural significance as the dividing line between the United States and Mexico, with the song "Rio Grande" and many literary works treating it as a symbol of the border.