Sweet Grass County Recreation Association is with Montana Snowmobile Association and Angie Roberts For Sweet Grass County Commissioner .

Published byLloyd Rue·April 17

Briefing: Main Boulder River Road in Park County and Sweet Grass County, Montana; Road Closure and Broken Bridges

(Provided to the Montana Snowmobile Association (MSA) leadership for their upcoming trip to Washington, DC, to meet with Montana Congressional delegation and staff.)

Introduction

The briefing outlines the loss of backcountry access to the Gallatin National Forest, south of Big Timber, Montana, following the closure of a road by Park County officials after two bridges collapsed during the 2022 flood, and the need to re-open the road for resource protection and restoring access to public and private property inholdings. The closure is about 50 miles south of Big Timber, along a road that meanders into and out of Sweet Grass and Park Counties and follows the Main Boulder River (see Figure 3).

Main Boulder Road History and Current Status

Historical Background

The Main Boulder Road was originally established in 1893, running entirely within Park County from the Chimney Rocks Pass near Cooke City, Montana, to the Boulder River Mining District. The shared jurisdiction of the route in the Boulder River Valley can be traced back to 1895 when Sweet Grass County was created from lands previously belonging to Park County. This joint oversight has continued since the road’s inception, which predates the creation of the Absaroka Forest in 1902—now known as the Custer Gallatin National Forest.

Geographic and Functional Significance

Located inside the Forest boundary, approximately 26 miles south of Big Timber, the Main Boulder Road serves as the main access route to the Absaroka-Beartooth Wilderness. The counties are responsible for owning and maintaining the road, even though they do not receive direct financial support for its upkeep. Importantly, this route provides access to Forest Service campgrounds and trailheads, serving area residents and visitors, and is the area’s only wintertime snowmobile trail.

Bridge Collapse and Funding Efforts

The collapse of two off-system bridges (Figure 1 and Figure 2) along the Main Boulder Road prompted Park County officials to secure partial funding from the State of Montana to rebuild the bridges and restore access. Additionally, Park County has applied for supplemental grant funding, also from the State of Montana, with the outcome of this request still pending. The bridges remain closed.

Alongside state-level efforts, Park County has submitted a partial funding request to Congressmen Sheehy and Daines, seeking further support for the reconstruction and reopening of the road.

Issues

The road's current condition limits access for emergency services and fire crews.  The closure blocks motorized entry to private land and motor vehicle access to maintain a communications site serving Sweet Grass and Park County. Park County has reduced its services and programs following Federal funding cuts last year. Summer visitation and its associated business income is down due to the closure.

County road departments, funded by property taxes in sparsely populated areas with extensive Federal lands, maintain large networks to reach remote locations. Federal funding is seldom pursued. Bridges built on the Boulder Road with federal funds between 1940-1955 provided safe access for over 75 years before being destroyed in 2022. Every year the road is closed—four and counting—the deterioration accelerates.

Solution

Provide supplemental funding to rebuild the off-system broken bridges, enabling construction to start next year and reopening the road by 2028. View this bridge funding as a priority for both Park County and Sweet Grass County. Reopening the road restores access to the Sweet Grass Co. segment, the communications tower, and private land. This supplemental, one-time funding will allow the corridor to be used safely for another 50-75 years, maintaining its current character.