Gardiner, MT, to Mammoth Hot Springs Professional Review and Guide
"A 5-mile drive from the oldest official Yellowstone entrance to Mammoth Hot Springs and old Fort Yellowstone, original home of the U. S. Cavalry when they were stationed in the park. Special Attractions: Ancient cliffs, the 45th Parallel, and elk.
Nearby points of interest: The Boiling River. This eTrail is a complete description of a scenic drive with a route map and information on the best travel seasons, interesting sites, recreation opportunities, camping locations, and much more."