Mountain passes in Custer Gallatin National Forest offer access to a vast expanse of over 3.1 million acres in Montana and a portion of South Dakota. This region features diverse landscapes, from rugged mountains to grasslands, supporting abundant wildlife. The forest's passes provide opportunities for recreation and connect various mountain ranges. It is a significant area for both natural beauty and historical routes.
Last updated: July 8, 2026
Highlight (Segment) β’ Mountain Pass
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Popular around Custer Gallatin National Forest
Unforgettable MTB Adventures β IMBA Epic Trails in USA and Canada
Hiking in Custer Gallatin National Forest
MTB Trails in Custer Gallatin National Forest
Road Cycling Routes in Custer Gallatin National Forest
Cycling in Custer Gallatin National Forest
Running Trails in Custer Gallatin National Forest

Gravel biking in Custer Gallatin National Forest
The north side of Beartooth Pass offers one of Montanaβs most challenging and scenic climbs, leading into the rugged Beartooth Mountains near the Wyoming border. Starting with a gradual incline, the road gradually steepens as it winds south, with breathtaking views of the valley and multiple switchbacks, some with exposed sections. By mile 22, the climb takes you above the treeline into stunning alpine terrain, crossing into Wyoming before a brief descent and a final push to the summit at 10,947 feet.
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Gorgeous remote gravel/dirt pass through the Bridger range. The west side is poorly-maintained and very loose, steep, and rutted in sections. If on a standard gravel bike, expect 1-2k of hike a bike. Bigger tires with a little suspension or a mountain bike are best here. Eastern descent is a bit rough in some sections but far better maintained and a gorgeous descent with breathtaking views of the eastern side of the Bridger Range that takes you through ranch lands, with bonus views of the Crazies in the distance. Grab water at the Pass Creek School or Community Center before heading in. If hot, be sure to bring a water filter, since there is no water for the next 30-40 miles, and this summit can take a long time.
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From Targhee Pass it is just 9 miles east to the town of West Yellowstone. For an easy day in/out of town, there are ample camping options littering the trail for about one mile headed north from the pass!
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The Reas Pass lies essentially on the Idaho-Montana border, but modern maps show that the summit lies entirely in Idaho, because the Divide and the state line do not quite coincide here. The pass is also somewhat unusual in that, despite being the lowest crossing of the Divide in the vicinity, it has evidently never been traversed by a highway of any significance.
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Beyond the popular Targhee Pass β Montana State Line, other significant passes include Sacagawea Pass in the Bridger Range, known for its challenging hike to Sacagawea Peak, and Bozeman Pass, which holds historical importance from the Lewis and Clark expedition. The Absaroka-Beartooth Wilderness also features passes that lead to unparalleled wilderness experiences.
Yes, for experienced hikers, Sacagawea Pass offers a challenging alpine hike through a glacial cirque towards Sacagawea Peak. Passes within the Crazy Mountains also provide remote and wild experiences with challenging hikes to alpine lakes. Additionally, the Absaroka-Beartooth Wilderness contains rugged, high-elevation passes perfect for backpackers seeking solitude and self-reliance.
Many passes offer stunning vistas. Sacagawea Pass provides expansive views of surrounding valleys and mountain ranges. Bozeman Pass offers breathtaking views of the peaks between the Gallatin, Bangtail, and Bridger ranges. The Flathead Pass Eastward offers gorgeous views of ranch lands and the Crazy Mountains. The Beartooth Pass Climb takes you above the treeline into stunning alpine terrain with panoramic views.
Yes, Targhee Pass β Montana State Line is considered family-friendly, offering ample camping options nearby. While many passes involve more strenuous activity, areas around Bozeman Pass also provide access to trails suitable for various activity levels, including hiking, mountain biking, and equestrian use.
The Custer Gallatin National Forest is rich in wildlife. Around Bozeman Pass, you might spot elk, deer, moose, grizzly bears, and cougars. The Absaroka-Beartooth Wilderness is home to moose, elk, mule deer, mountain goats, and bighorn sheep. Always be aware of your surroundings and practice Leave No Trace principles.
Yes, Bozeman Pass is historically significant as it was traversed by Sacagawea in 1806 during the Lewis and Clark expedition. The Crazy Mountains also hold cultural significance for the Crow Nation, who have a deep spiritual connection to the area.
The region offers a wide range of activities. You can find numerous running trails, including loops near West Yellowstone and Sacagawea Peak. There are also easy hikes like Ousel Falls Trail and Silver Run Trail. For cyclists, challenging road cycling routes like the Beartooth Pass Climb are available. Explore more options on the Running Trails, Easy Hikes, and Road Cycling Routes guides for the Custer Gallatin National Forest.
Yes, the Absaroka-Beartooth Wilderness, accessible via its passes, features active glaciers and hundreds of alpine lakes. The Crazy Mountains also boast over 40 jewel-like alpine lakes, providing excellent opportunities for trout fishing and stunning scenery.
The best time to visit is generally from late spring through early fall (June to September) when the passes are typically clear of snow and weather conditions are more favorable for outdoor activities. However, conditions can be unpredictable at higher elevations, especially in the Absaroka-Beartooth Wilderness, so always check local forecasts before your trip.
For a more remote experience, consider passes within the Crazy Mountains, which offer a wild and isolated landscape. The Absaroka-Beartooth Wilderness also provides extensive opportunities for solitude due to its vastness and rugged terrain, making it a 'backpacker's dream' for those seeking less crowded areas.
Visitors frequently praise the breathtaking views, the challenging yet rewarding climbs, and the sense of remote wilderness. Many appreciate the diverse landscapes, from rolling hills to rugged alpine terrain, and the opportunities for wildlife sightings. The historical significance of certain passes also adds to the rich experience.


See even more epic mountain passes by checking out these guides in Custer Gallatin National Forest: