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Project Overview

The Montana Department of Transportation (MDT) is designing improvements to US Highway 89 (US 89) between Sun River and 1st Road South in Cascade County. The project begins at the junction of US 89 and Montana Highway 200 (MT 200) and extends approximately nine miles northwest, ending about half of a mile southeast of 1st Road South.

Project map

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The project will reconstruct approximately nine miles of roadway and replace five bridges. The roadway will be shifted in some locations to reduce impacts to developed properties and avoid environmentally sensitive areas.

The design plans will include:

  • Reducing the steepness of slopes on the side of the road.
  • Reducing the grade (steepness) of vertical hills.
  • Replacing five bridges.
  • Adding six-foot shoulders.
  • Adding a new gravel base and pavement.
  • Adding shoulder rumble strips.
  • Replacing centerline rumble strips.

Project Purpose

US 89 Sun River to 1st Road South project location photo

The purpose of this project is to enhance safety features and help reduce roadway departure crashes. This section of US 89 was built in the 1940’s and has areas with steep slopes on the side of the road, rolling hills, and narrow shoulders. Roadway safety enhancements in this area will help reduce the risk of roadway departure crashes.

  • From 2008 through 2017, the Montana Highway Patrol reported 81 crashes along this corridor, with the main crash trend being roadway departure crashes.

Stay Involved

MDT will notify the community about public involvement opportunities through this website, local media, mailings, social media and other communication channels throughout the project development process.

MDT encourages members of the public to join the project's mailing list by submitting their contact information to Brandon Coates via email.

UPN 9536000