After 1872 when Yellowstone National Park was established, the park was under serious threat from those who would exploit its resources, rather than protect them. There were many instances where poachers killed animals, souvenir hunters broke large pieces off the geysers and hot springs, and developers set up camps for tourists, along with bath and laundry facilities at some of the hot springs.

Civilian superintendents were hired to preserve and protect this land from 1872 through 1886. The good intentions of these early administrators, however, were no match for their lack of experience, funds and manpower.

Word got back to Congress in 1886, that the park was in trouble, however, legislators refused to appropriate any funds for the administration of the park.

The Secretary of the Interior, invoked the Sundry Civil Act of 1883, and called upon the Secretary of War for assistance in protecting the park. The Army came to the rescue and in 1886 men from Company M, First United States Cavalry, Fort Custer, Montana Territory under Captain Moses Harris came to Yellowstone to begin what would be more than 30 years of military presence in Yellowstone.

When Company M arrived in August 1886, they lived in temporary frame buildings at Camp Sheridan, which has been established at the foot of the Mammoth Hot Springs Terraces. Only after enduring five cold, very harsh winters, the cavalry realized there was no end in sight to this assignment. Therefore, in 1890, Congress appropriated $50,000 for a permanent post.

In 1891, the very first building constructed was the guard house because it directly coincided with the mission of the Cavalry, that to protect and manage the park. Following that, there was next three stages to the construction at Fort Yellowstone. Stage One in 1891: the first set of clapboard buildings were built. Stage Two in 1897: the second set of clapboard buildings were built when the Fort expanded into a two-troop fort. Stage Three in 1909: the stone buildings were built in 1909 increasing the capacity of the fort to four troops, or 400 men.

The Mammoth Hot Springs Historic District includes Fort Yellowstone, where 35 structures remain from the 1890s and early 1900s during the time when the US Army administered the park. Significant conservation policies were developed here that led to the origin of the National Park Service.

The buildings in the historical district represent the first development of administrative and concession facilities in the park.

The Mammoth Hot Springs Historic District has statewide significance as the administrative and concession headquarters of the largest national park in Wyoming. Fort Yellowstone is also listed as a National Historic Landmark District, the highest designation given to an historic fort.

By 1916, the National Park Service was established and the US Army moved out. In 1917, The Army returned and finished their duty until the end of 1918 when the management was turned over to the National Park Service. Since that time, historic Fort Yellowstone has been the headquarters for Yellowstone National Park.

The Fort Yellowstone-Mammoth Hot Springs Historic District is in the northwestern portion of Yellowstone National Park on an old hot springs formation.