Fawn Pass Trail

Fawn Pass Trail is a strenuous 21-mile, one-way crossing of Yellowstone’s Gallatin Range. Start at Fawn Pass Trailhead (WK5) near U.S. 191 and finish at Glen Creek Trailhead south of Mammoth. The route climbs over Fawn Pass, then descends through forest and meadows to the other side of the range. Allow a full day on trail—about 12 hours—and arrange a shuttle or leave a vehicle at both ends before you start. The west-side park listing gives 21 miles; the Glen Creek listing gives 19.7 miles in the other direction, so plan around the longer figure.

The route begins near Fan Creek and moves through a mix of forest and riparian meadow. As you climb toward Fawn Pass, trees thin and the terrain opens into broad alpine country. The park describes about 2,030 feet of climbing over the pass. This is a long approach, so the best reason to keep going is the change from forest and meadow to the open high country.

Fawn Pass is the high point and the main payoff: a saddle in the Gallatin Range with open views across the mountains. On the far side, the route continues through meadows and forest, following the Fawn Creek and Glen Creek corridors toward the finish. If you stop for a photo in the open meadow, keep some trail in the foreground; it shows the scale of the crossing better than the ridges alone.

This is not a loop. The west end is Fawn Pass Trailhead (WK5) on U.S. 191; the east end is Glen Creek Trailhead south of Mammoth. The 18-mile out-and-back to Fawn Pass is the alternative if you need to return to WK5, though that is still a strenuous day. An overnight stay requires a backcountry permit; the trail pages list no permit for day hiking.

Grizzlies frequent this corridor. Carry bear spray and know how to use it; the park recommends groups of four on this trail. From May 1 through November 10, stay on designated trails in the bear management area. Pets aren't allowed.