About 1,450 miles · 7 basin states · source Rocky Mountain NP, CO · mouth Gulf of California
Colorado River map
The Colorado runs about 1,450 miles from the Rocky Mountains of Colorado through Utah and Arizona to the Gulf of California in Mexico, forming the Arizona–Nevada and Arizona–California borders.
Where the Colorado is
The river rises at La Poudre Pass in Rocky Mountain National Park, Colorado, at about 10,180 ft, and flows southwest for about 1,450 miles. It crosses western Colorado, cuts through the canyon country of southeastern Utah, enters Arizona at Lake Powell, carves the Grand Canyon, then turns south to form Arizona's border with Nevada and California before crossing into Mexico. In most years it no longer reaches the sea; irrigation and city water take nearly all of it before the delta.
States in the basin
The 1922 Colorado River Compact divides the water between seven states. The Upper Basin is Colorado, New Mexico, Utah and Wyoming; the Lower Basin is Arizona, Nevada and California. Wyoming and New Mexico do not touch the mainstem: they contribute through the Green and San Juan rivers. Mexico receives a fixed share under a 1944 treaty.
Key measurements
- Length: about 1,450 miles; basin about 246,000 square miles.
- Main tributaries: the Green (from Wyoming, joins in Canyonlands), the Gunnison, the San Juan, the Little Colorado and the Gila (joins at Yuma).
- Hoover Dam (1936), on the Arizona–Nevada line, holds back Lake Mead, the largest reservoir in the US by capacity.
- Glen Canyon Dam (1963), just inside Arizona, holds Lake Powell, the second largest.
- The Grand Canyon section is 277 river miles long and about a mile deep.
Cities on or near the river
Grand Junction, Colorado, sits at the Gunnison confluence. Moab, Utah, and Page, Arizona, are the gateway towns for Canyonlands and Lake Powell. Las Vegas is 30 miles from Hoover Dam and draws about 90 percent of its water from Lake Mead. Downstream are Laughlin, Lake Havasu City and Yuma. Off the river but dependent on it: Phoenix, Tucson, Los Angeles and San Diego, all served by aqueducts.
How the river shaped the map
The river forms about 300 miles of state boundary: the Arizona–Nevada line from the Utah corner to below Lake Mohave, then the Arizona–California line to the Mexican border. California's diagonal southeastern edge was drawn to meet the river in 1850. In the upper basin the borders ignore the river entirely and follow surveyed meridians, which is why the Four Corners sits on a plateau the river has cut into.
Related maps
- Grand Canyon — the river's most famous stretch.
- Colorado Plateau — the country it flows through.
- Mojave Desert and Sonoran Desert — the lower river's setting.
- Longest US rivers · All geography maps.