The Maah Daah Hey Trail is a 96-mile (154-kilometer) trail that connects the northern and southern portions of Theodore Roosevelt National Park, and winds through the Little Missouri National Grasslands in North Dakota's Badlands to form the longest continuous singletrack mountain biking trail in America.
Maah Daah Hey is a phrase from the Mandan Indians meaning "an area that has been or will be around for a long time."
The trail begins a few miles south of Medora at Sully Creek State Park and ends at CCC campground near the North Unit of Theodore Roosevelt National Park. The trail connects both the North Unit and South Unit, although biking is not allowed in the parks themselves. Alternate bike trails have been constructed to bypass the parks. The entire trail is open however, to hikers and horseback riders. There are multiple trailhead entry points which can be accessed from US 85 and country roads on the west side of the Little Missouri River.