Colorado River (US)

Colorado River
The Colorado River at Horseshoe Bend, Arizona, a few miles below Glen Canyon Dam
Countries	United States, Mexico
States	Colorado, Utah, Arizona, Nevada, California, Baja California, Sonora
Tributaries
- left	Fraser River, Blue River, Eagle River, Roaring Fork River, Gunnison River, Dolores River, San Juan River, Little Colorado River, Bill Williams River, Gila River
- right	Green River, Dirty Devil River, Escalante River, Kanab River, Virgin River, Hardy River
Cities	Glenwood Springs, CO, Grand Junction, CO, Moab, UT, Page, AZ, Bullhead City, AZ, Lake Havasu City, AZ, Yuma, AZ, San Luis Rio Colorado, SON
Source	La Poudre Pass
- location	Rocky Mountains, Colorado, United States
- elevation	10,184 ft (3,104 m)
- coordinates	40°28′20″N 105°49′34″W / 40.47222°N 105.82611°W / 40.47222; -105.82611
Mouth	Gulf of California
- location	Colorado River Delta, Baja California–Sonora, Mexico
- elevation	0 ft (0 m)
- coordinates	31°54′00″N 114°57′03″W / 31.90000°N 114.95083°W / 31.90000; -114.95083Coordinates: 31°54′00″N 114°57′03″W / 31.90000°N 114.95083°W / 31.90000; -114.95083
Length	1,450 mi (2,334 km)
Basin	246,000 sq mi (637,137 km2)
Discharge	for mouth (average virgin flow), max and min at Topock, AZ, 300 mi (480 km) from the mouth
- average	22,500 cu ft/s (637 m3/s)
- max	384,000 cu ft/s (10,900 m3/s)
- min	422 cu ft/s (12 m3/s)
Map of the Colorado River basin

The Colorado River is one of the principal rivers of the Southwestern United States and northern Mexico (the other being the Rio Grande). The 1,450-mile-long (2,330 km) river drains an expansive, arid watershed that encompasses parts of seven U.S. and two Mexican states. Starting in the central Rocky Mountains in the U.S., the river flows generally southwest across the Colorado Plateau and through the Grand Canyon before reaching Lake Mead on the Arizona–Nevada border, where it turns south toward the international border. After entering Mexico, the Colorado approaches the mostly dry Colorado River Delta at the tip of the Gulf of California between Baja California and Sonora.

Known for its dramatic canyons, whitewater rapids, and eleven U.S. National Parks, the Colorado River system is a vital source of water for 40 million people in southwestern North America. The river and its tributaries are controlled by an extensive system of dams, reservoirs, and aqueducts, which in most years divert its entire flow for agricultural irrigation and domestic water supply. Its large flow and steep gradient are used for generating hydroelectric power, and its major dams regulate peaking power demands in much of the Intermountain West. Intensive water consumption has dried up the lower 100 miles (160 km) of the river, which has rarely reached the sea since the 1960s.

Beginning with small bands of nomadic hunter-gatherers, Native Americans have inhabited the Colorado River basin for at least 8,000 years. Between 2,000 and 1,000 years ago, the river and its tributaries fostered large agricultural civilizations – some of the most sophisticated indigenous cultures in North America – which eventually faded due to a combination of severe drought and poor land use practices. Most native peoples that inhabit the basin today are descended from other groups that settled in the region beginning about 1,000 years ago. Europeans first entered the Colorado Basin in the 16th century, when explorers from Spain began mapping and claiming the area, which later became part of Mexico upon its independence in 1821. Early contact between Europeans and Native Americans was generally limited to the fur trade in the headwaters and sporadic trade interactions along the lower river.