River, east-central Arizona, U.S. A tributary of the Gila River , it is formed at the confluence of the Black and White rivers.
It flows west 200 mi (320 km) and empties into the Gila River southwest of Phoenix . It is part of the Colorado River drainage basin. A system of dams forms a chain of lakes that provides hydroelectric power. In pre-Columbian times the river valley was cultivated by Hohokam Indians who constructed systems of irrigation canals.