MDT Closes Highway 91 Bridge Over Big Hole River

Through traffic between Melrose and Glen can detour via I-90.

DILLON, Mont. — The Montana Department of Transportation (MDT) has closed the Big Hole River Bridge on Highway 91 (Hwy 91) approximately 22 miles north of Dillon. All traffic is prohibited from using the bridge. After a scheduled inspection determined the structure cannot continue to carry traffic safely or reliably, MDT immediately implemented the closure. Previously, the structure was load posted for 3 tons, and traffic was restricted to one lane.

The bridge was built in 1940 and is a steel through truss with reinforced concrete approach spans. A project to replace the bridge is included in MDT’s tentative construction program with a target contract letting for Fall 2026.