This is a list of dams on the Colorado River system of the southwestern United States and northwestern Mexico. The Colorado runs 1,450 mi (2,330 km) from the Rocky Mountains to the Gulf of California, draining parts of seven U.S. states and two Mexican states. The river system is one of the most heavily developed in the world, with fifteen dams on the main stem of the Colorado and hundreds more on tributaries. Collectively, dams in the Colorado River basin can hold four to five times the river's annual flow, generating hydroelectricity and supplying irrigation and municipal water for over 35 million people.