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US-191 Wildlife and Transportation Conflict Assessment: Preparing for Continued Growth

Project #: 4W9061
Start Date: 05/01/2021
End Date: 09/30/2022
Status: Completed
Residents, Commuters, and Visitors Depend on these Roads:

More Traffic is a Problem for Wildlife:

The Status Quo is Risky and Expensive:

  • Traffic volume along US-191 increased by 38% from 2010-2018.
  • 83% of Big Sky workers regularly commute along US-191 and MT-64 (Lone Mountain Trail).
  • Visitation to Yellowstone National Park increased by 20% from 2014-2017 and over 1 million trips on US-191 are made to enter the park. The town of West Yellowstone
  • hosts more than 4 million visitors per year.
  • Grizzly bears, among other species, are sensitive to traffic, losing road crossing opportunities as levels increase
  • Traffic on US-191 and MT-64 is already at a level that has been shown to reduce deer crossing safety

Collisions involving wildlife make up 24% of all reported crashes on US-191 and over 13% on MT-64.a,b Across Montana, the statewide average is 10%, while the national average is 5%.

A driver in Montana has a 1 in 53 chance of hitting an animal every year—the second highest of any state in the nation. 1 in 127 is the average chance across the U.S.

Citizen Science Data Portal: An accompanying data website has been created allowing citizens to record sightings of live and roadkilled animals and describe important wildlife movement areas along the US-191 and Lone Mountain Trail road corridors.


Roads sever intact landscapes and serve as one of the greatest threats to wildlife habitat connectivity. Historically, Montana’s iconic species moved freely to and from Yellowstone National Park and habitat in the 1.8-million-acre Gallatin National Forest. This movement is now threatened by higher traffic volumes, road noise, and reduced habitat quality along US-191. Wildlife along busier roads also pose a greater risk to human safety, affecting residents, commuters, and tourists. State Farm Insurance ranks Montana second highest in the U.S. for risk of wildlife-vehicle collision.

Measures to mitigate wildlife-vehicle collisions have been used in Europe since the 1950s and are now regular features in Wyoming, Arizona, and Nevada, among other states. The Center for Large Landscape Conservation recently carried out a habitat connectivity analysis of the Custer-Gallatin national Forest and is poised to help Big Sky achieve its vision of “a community actively working to grow, while…preserv[ing] its natural ecosystem” by developing a robust and publicly vetted assessment and mitigation plan for wildlife-vehicle conflicts in the area. The assessment will serve as a foundational step in road redevelopment planning and prepare Big Sky for implementation opportunities using methodologies already applied on the Blackfeet Indian Reservation and in Teton County, Wyoming. This is the first of two phases of this project. Phase 1 is funded by the US Federal Highway Administration and the Big Sky Resort Area District.


The goal of this project is to develop a state-of-the-art Wildlife and Transportation Conflict Assessment for terrestrial and aquatic species along US-191 from Gallatin Canyon to West Yellowstone, and along Lone Mountain Trail, in Montana, to:

  1. Lay the groundwork for implementation of best management practices to protect wildlife and human safety in the face of unprecedented regional traffic growth.
  2. Provide residents and officials of communities along US-191 with essential tools to guide decision making.
  3. Enable public agencies to prioritize win-win design in future road development.