Colorado River (U.S.)

The Colorado River is a 1,450-mile-long river whose headwaters are at the continental divide in the center of Colorado. From there, it flows southwest and south through several U.S. states including Utah, Arizona, Nevada, and California. It then crosses Mexico between Baja, California and Sonora to flow into the Gulf of California. It passes through 11 different national parks and monuments as it tumbles through the varied landscapes, including the Grand Canyon and Hoover Dam.

Large-scale river management began in the early 1900s. Located in an arid region and with all of its waters fully allocated, there is more demand for its waters than can be accommodated, resulting in extensive ongoing legal battles. In particular, the lower Colorado provides water to Las Vegas, Los Angeles, San Diego, Phoenix, and Tucson.