The river drains an arid watershed of nearly 60,000 square miles (160,000 km2) that lies mostly within the U.S., but also extends into northern Sonora, Mexico.

Indigenous peoples have lived along the river for at least 2,000 years, establishing complex agricultural societies before European exploration of the region began in the 16th century.

The engineering projects transformed much of the river valley and its surroundings from arid desert into irrigated land, and supply water to more than five million people in the Phoenix and Tucson metropolitan areas who live in the watershed.

[8] Their traditional way of life (himdagĭ, sometimes rendered in English as Him-dak) was and is centered at the river, which is considered holy.

The first European to see the Gila River was possibly Spanish explorer and missionary Juan de la Asunción.

Asunción reached the Gila in 1538 after traveling northwards along one of its tributaries, either the San Pedro or Santa Cruz.

[11] During the Mexican–American War, General Stephen Watts Kearny marched 100 cavalrymen from the 1st U.S. Dragoons along the Gila River in November 1846.

The Mormon Battalion followed Kearny's troops, building a wagon trail roughly following the river from December 1846 to January 1847.

Devising a scheme to flee by water, the Germans constructed a collapsible kayak under the noses of their American captors, tested it in a makeshift pool within the prison compound, then sneaked it out through the tunnel.

Others, such as Coolidge Dam, are owned by local water supply agencies, irrigation districts, or Native American tribes.

During his time in office, former New Mexico Governor Bill Richardson had promised to block any such attempt during his term, and he had even considered pushing for a statutory prohibition against any such projects on the state's portion of the river.

[18] The Gila River between Virden, New Mexico, and Solomon, Arizona, is navigable during spring snowmelt and after summer and autumn storms.

Due to its desert surroundings, the river is characterized by erratic flows and flash floods that reach high peaks and drop off just as quickly.