Wild horses have long roamed the Pryor Mountains, but there was a time when the herd was in serious danger of going extinct. In the past, efforts were made by the government to remove all wild horses from the Pryors. By the late 1950’s, the wild horse population was significantly lowered; and a group of local citizens fought the Bureau of Land Management, who was planning to remove the remaining members of the herd. After a legal battle, these citizens emerged victorious, and the Pryor Mountain Wild Horse Range was born.
The Pryor Mountain Wild Horse Range was established in September of 1968 by Secretary of the Interior Stewart Udall. Such an action was groundbreaking; the PMWHR was the first public wild horse range established in the United States. It also preceded the writing of the Free-Roaming Wild Horse & Burro Act 1971 by three years, though the passing of the 1971 act allowed the PMWHR to be expanded. Since then, the range boundary has changed; and today it covers over 38,000 acres of land. The PMWHR straddles the Montana-Wyoming border and covers Forest Service, National Park Service, and Bureau of Land Management land, though the BLM oversees horse-related activities.