The fort was located within a massive military reservation stretching south to the Missouri River, north to the Milk River and containing the Bear's Paw Mountains. It encompassed 704,000 acres (1,100 sq. mi., 2850 km2) at its maximum extent in 1880. It later was reduced to encompass 220,000 acres (344 sq. mi., 890 km2). At its peak, it garrisoned more than 750 officers and enlisted men and their families. With 104 buildings, the fort was one of the largest ever built in the United States.