The All-American Canal is an aqueduct in southeastern California. It conveys water from the Colorado River into the Imperial Valley and to nine cities. It is the Imperial Valley's only water source, and replaced the Alamo Canal, which was located mostly in Mexico. The Imperial Dam, about northeast of Yuma, Arizona, on the Colorado River, diverts water into the All-American Canal, which runs to just west of Calexico, California, before its last branch heads mostly north into the Imperial Valley. Five smaller canals branching off the All-American Canal move water into the Imperial Valley. These canal systems irrigate up to of good cropland and have made possible a greatly increased crop yield in this area, originally one of the driest on earth. It is the largest irrigation canal in the world, carrying a maximum of . Agricultural runoff from the All-American Canal drains into the Salton Sea. The All-American Canal runs parallel to the Mexico–United States border for several miles.