Later, the camp served to protect the Cheyenne and Arapaho reservations from incursions by white settlers and in 1878 was renamed Fort Supply following its role in the Red River War of 1874-1875. The post was also responsible for safely escorting cattle drives along the trails from Texas to Kansas.

By 1880, the Indian Wars on the Southern Plains were over and the post was in bad repair. Though the Department of Missouri recommended its closing, General Philip Sheridan opposed the idea and worked to establish the Fort Supply Military Reservation. It soon became a hub of transportation, with troops building roads and telegraph lines that linked the forts and reservations, as well as protecting travelers along the many trails.

Following the opening of the Cherokee Outlet to white settlement, Fort Supply was officially closed in September, 1894, and turned over to the Department of Interior.

In 1908, Oklahoma's first state-operated mental institution was established at the old post and which is now called the Western State Psychiatric Center. In 1969, the Oklahoma Historical Society assumed responsibility for the five remaining army period buildings which were designated as a National Historic District in 1971.

Since 1998, the William S. Key Correctional Center, a minimum security prison facility, has occupied most of the old post and hospital grounds.

Today; however, the remaining buildings, including the Ordnance Sergeant's Quarters, Civilian Employee Quarters, Officers’ Quarters and a Guard House can still be seen. A Visitor’s Center and Museum are also available for visitors.

East of the old post on US 270 is the old Fort Supply Cemetery. Though it includes numerous historic graves, the soldiers who were formerly buried here were moved to Leavenworth, Kansas when the fort was officially closed.

The historic post is located in Fort Supply, Woodward County, in northwest Oklahoma.