Yuma, Arizona, the seat of Yuma County. It is on the Colorado River at the mouth of the Gila River, about 160 miles (257 km) southwest of Phoenix. Yuma is a transportation and trading center for an irrigated farmland area. The Fort Yuma Indian Reservation is across the Colorado River, in California. Imperial and Laguna dams are nearby. Yuma was founded in 1849. Earlier names were Colorado City and Arizona City. Yuma has the council-manager form of government.