Name / Description

Colorado River





Length (miles)


Size (sq. miles)


Part of / Flows into

Northern end of Gulf of California/Pacific


Mostly SWestern US; 95 miles in Mexico

Additional Notes

1,450 miles long; SW U.S., rising in the Rocky Mts. of N Colo., in NW Rocky Mt. Natl. Park, NE Grand co., 25 miles NNE of Granby, 65 miles NW of Denver, and flowing generally SW through Colo., Utah, Ariz., bet. Nev. and Ariz., and Ariz. and Calif., and then into Mexico, emptying into the Gulf of California; drains c.244,000 sq miles. Source is surrounded on 3 sides by Continental Divide; flows S through Grand L. (Shadow Mt. Reservoir) and L. Granby reservoirs, then generally SW past Glenwood Springs, Rifle, and Grand Junction, Colo., where it receives the Gunnison R. from SE, into Utah, where it forms the S boundary of Arches Natl. Park at Moab, then through Canyonlands Natl. Park, where it receives the Green R., its longest tributary from the N. The Colorado then enters Glen Canyon Natl. Recreational Area and L. Powell, formed by the Glen Canyon Dam at Page, in extreme NE Ariz., and at 26,997,000,000 cu ft, the 2d largest reservoir in U.S. Receives the San Juan R. from E. Below Glen Canyon Dam, the river enters Marble Canyon and Grand Canyon natl. parks. (The river and part of L. Powell form NW boundary of Navajo Indian Reservation.) Due to major park expansion in 1975, the river flows c.140 miles through the park, through Marble Canyon and the spectacular Grand Canyon; then for another 100 miles it forms the S boundary of the W extension of the park and N boundary of Hualapai Indian Reservation. It then enters L. Mead Natl. Recreational Area (at 28,253,000,000 cu ft, L. Mead, formed by Hoover Dam, is the largest reservoir in the U.S). The river flows almost due S. Below Davis Dam, it flows through Fort Mohave Indian Reservation and becomes Calif.-Ariz. state line. Just E of Yuma, the Colorado receives the Gila R. from E. For c.20 miles below Yuma, the river forms part of the U.S.-Mexico border (Ariz. to E, Baja California Norte to W). Its final 95 miles reduced to a braided trickle, flows through Mexico, forming border bet. Baja California Norte and Sonora states, entering the N end of the Gulf of California.