Fort Grant began its life as an Old West fort in Arizona Territory, built in 1860 at Aravaipa Canyon as "Old Camp Grant."
In 1872, the U.S. Army fort was relocated to the southwestern slope of Graham Mountain in what is now Graham County. The fort was strategically placed so as to protect settlers who were constantly harassed by Apache warriors. It played a prominent role in the Apache Wars of the 1880s. It was repurposed in 1900 as a staging point for soldiers going to the Philippines to fight the Spanish-American War.
Fort Grant was abandoned in 1905 by the Army, which transferred all troops to Fort Huachuca and left the fort unoccupied except for a caretaker. In 1912, Arizona gained statehood, and the fort was occupied by the Fort Grant State Industrial School, which modernized most of the buildings.
In 1968, the state of Arizona officially assigned the site to the Department of Corrections, and in 1973 Fort Grant became a state prison for male convicts. In 1997 the prison became a unit of an Arizona State Prison complex headquartered in Safford.
The main road to and from Fort Grant is Arizona State Route 266. There is an abandoned general-aviation airport, Angel Field, immediately south of the prison.