Mary Mountain Trail

Overview

This is Yellowstone’s big, wild point-to-point across the park’s center—20.2 miles one way that roll through Hayden Valley and the Central Plateau. Expect long miles with minimal elevation change, little shade, and true backcountry conditions. The payoff: sweeping big‑sky views, huge bison country, and a real chance of seeing grizzly sign (and sometimes the bears themselves). If you want a quintessential Yellowstone backcountry day that feels remote without crazy climbing, this is it.

Route & Highlights

Most hikers start east and head west across Hayden Valley toward the geyser country. Roughly halfway you reach Mary Lake with nearby backcountry thermal areas, including Violet Springs and Highland Hot Springs. You’ll alternate between open meadows and pockets of forest. Bison carve their own “Buffalo Highway” paths that can tempt you off course; the official route uses orange stick markers (about every half mile), but they’re sometimes knocked down. Carry a real map/GPS and be comfortable navigating broad meadows.

Logistics

There are two trailheads. The east start sits near where Alum Creek meets the Yellowstone River, about 4 miles from Canyon Junction. The west start is roughly 9.5 miles from Old Faithful Junction near Porcupine Hill Geyser. Both have only small roadside turnouts and no facilities—arrive early. This is usually done as a shuttle; very few attempt an out‑and‑back. There are multiple creek fords along the route; expect wet feet and bring trekking poles. The trail can be muddy in early summer.

Best Time to Hike

The trail is closed March 10–June 15 for bear management. Outside that window, early season brings wetter, deeper fords and more mud; late summer generally means lower water and drier tread. August coincides with the bison rut—give bulls extra space. Start at dawn for cooler temps, fewer animal traffic jams, and all the daylight you can get. If thunderstorms build, get off ridges and out of open high points.

Wildlife & Safety

Grizzlies frequent this corridor—carry bear spray, hike in a group, make noise in brushy sections, and steer clear of carcasses or concentrated bear sign. Give at least 100 yards to bears and wolves, 25 yards to bison and other wildlife, and detour widely around animals on the trail. Thermal features near the route can scald; stay on firm ground and off fragile crust. No pets. Don’t hike after dark. Park waters are swift and cold—treat every crossing with respect.

Is it worth it?

If you’re up for a long, committing day with wildlife drama and classic Yellowstone scenery, absolutely. It’s not a groomed “greatest hits” boardwalk—expect route‑finding, bison delays, wet feet, and the real possibility of changing plans on the fly. That’s the charm.