The Mammoth District of Yellowstone contains a number of constantly shifting and changing hot springs. The springs are formed by hot water rising through limestone, resulting in travertine deposits.

When John Colter, a member of Lewis and Clark’s Corps of Discovery, described the hot springs of Yellowstone, his story was met with ridicule and the area became derisively known as “Colter’s Hell.” On August 17, 1806, Colter left the Corps of Discovery to explore the Yellowstone River with two other trappers. Colter did not leave an account of his journey and the only written evidence of his exploration is third hand. There are some traces of physical evidence, however, which indicate Colter did make the journey he claimed.

This area also contains the Fort Yellowstone-Mammoth Hot Springs Historic District, which houses the administrative offices for the national park. In an attempt to protect the area from poachers and souvenir hunters, the military took control of the administration of Yellowstone shortly after it was created. In 1890, Congress appropriated $50,000 for the protection of the park, and the army began construction of what would become Fort Yellowstone.

In 1923, Frank Tolhurst won the first U.S. mail contract in Yellowstone, and the mail service operated from a main post office located in the Mammoth area. His contract was short-lived, however, and the government discontinued it in 1928. As tourism to the park increased during the 20th century, companies built hotels, cabins, gas stations, and baths for visitors.

Researched, written, and narrated by University of West Florida Public History Student Michael Lawhorne