Going-to-the-Sun Road, Marias Pass, Rogers Pass, MacDonald Pass, Snobowl, and high-country routes — open or closed, with elevation, season, and restrictions for each pass.
The crown jewel of Glacier National Park — 50 miles of engineering marvel with 11 switchbacks.
The lowest Cascades crossing in the Continental US. Historic BNSF railway corridor. East-west lifeline for Glacier NP south entrance.
Montana most avalanche-prone corridor. Active slide paths above highway. Multiple winter closures per season.
Going-to-the-Sun Road is the most iconic scenic drive in North America — 50 miles of engineering daring with 11 switchbacks, two tunnels, and views that define Glacier National Park. The road crosses the Continental Divide at Logan Pass (6,646 ft) and drops to 3,466 ft at the West Glacier tunnel.
Seasonal constraints are severe: the road typically closes from late October through late May due to snowpack and avalanche hazard. Even at opening, vehicle restrictions apply — maximum length 21 feet (26 feet with escort) due to tunnel dimensions. High-profile vehicles and vehicles with trailers are prohibited on the full route.
2026 update: Glacier National Park requires timed-entry reservations for all vehicles entering the park in 2026 — book at recreation.gov before your trip. No walk-up or same-day entry without a reservation. The reservation system operates May 23 – September 8, 2026.
Rogers Pass on US-2 — the 20-mile segment between Essex and St. Mary — is Montana most avalanche-prone highway corridor. Steep avalanche paths above the road are systematically triggered by USFS during winter control operations, resulting in multi-hour or multi-day seasonal closures every year.
The pass sits at 5,610 ft elevation, making it one of the highest trans-Cascades highway routes in the lower 48. During active storm cycles, MDT may perform rolling closures for avalanche control — these can last 30 minutes to 8 hours. Even after the road reopens in spring, lingering wet avalanche hazard persists on north-facing slopes above the highway.
This corridor also forms the north entrance to Glacier National Park. When Rogers Pass is closed, the park West Side cannot be accessed from the east. The Flathead Avalanche Center (flatheadavalanche.org) covers this zone — check their forecast before crossing during the should-seasons.
Marias Pass (5,233 ft) is the lowest crossing of the Cascades in the Continental United States — a fact that makes it both the most reliable and the most busy east-west Montana route. The BNSF railway also runs through the pass, making it one of the most critical freight corridors in the Pacific Northwest.
Unlike Rogers Pass, Marias Pass is maintained as a year-round highway. The route is well-engineered and plowed, though chain/traction laws apply during winter storms. The pass is the primary access for visitors driving from the east (Great Falls, Shelby, Cut Bank area) to the Glacier Park West entrances and the Flathead Valley.
The pass was named by the 1854 expedition of Lt. George Mercer — a brief window of favorable weather allowed his team to cross what they named after the nearby river. Check MDT 511 (511.mt.gov) for real-time conditions, chain laws, or construction delays.
The "Trenches" refers to the North Fork Flathead River corridor — the remote, unpaved forest roads that form the western boundary of Glacier National Park and the access to the Bob Marshall Wilderness. Key routes include the North Fork Road (County Road 538), N Fork Road/Mullan Road, and the access to Polebridge.
The Blankenship Bridge is the critical structure — a low-water ford crossing of the North Fork Flathead River. When the river is low (typically May–October), the crossing is passable. When river levels rise with spring runoff or heavy rain, the crossing becomes impassable. The bridge typically closes in late October or November and reopens in late April or May.
When the Blankenship Bridge is closed, the only access to Polebridge and the North Fork corridor from the US side is via the Canadian border crossing at Rooseville/Polebridge (open seasonally) or via an extremely long detour through Glacier Park and the Inside North Fork route. High-clearance 4WD is strongly recommended. No services (fuel, food, lodging) for 30+ miles on these roads.