At about 260 feet, Union Falls is the second-tallest waterfall in Yellowstone, fanning out dramatically in the remote Bechler (Cascade Corner) region. Reaching it requires a long backcountry day hike or backpack of roughly 16 miles round trip.
At 260 ft, it stands above roughly 91% of the 775 documented falls in this guide.
The falls are fed by Mountain Ash Creek. You'll find it in Teton, Wyoming. It is protected within National Park Service (Yellowstone National Park).
This is a backcountry waterfall: a remote, long, or permit-required trek for prepared visitors. Getting there takes a genuine backcountry effort, so come prepared with navigation, water, and enough daylight. The walk to the main viewpoint runs about 15.6 miles round trip. Base a visit out of Ashton, Idaho, the closest town.
When to go: Mid-July to September. Like most waterfalls, Union Falls runs highest after snowmelt or heavy rain and can thin out in late summer, so it's worth checking recent streamflow and the land manager's conditions page before a long drive.
