Historic U.S. 10

Painted shields for U.S. 10 and U.S. 12 remained on the BNSF Main Street Overpass along Business Loop I-94/MT 59 in Miles City, 30 years after U.S. 10 was truncated east to North Dakota. - 08/07/2016

U.S. 10 in Montana was replaced by Interstate 90 east from Lookout Pass on the Idaho state line east to Missoula an Garrison. U.S. 10 partitioned into U.S. 10N from Garrison east to Helena and south to Townsend, and U.S. 10S south to Warmsprings and east to Butte. The two branches converged west of Three Forks, where U.S. 10 resumed southeast to Bozeman.

Interstate 90 again replaced U.S. 10 from Logan east to Bozeman, Livingston, Big Timber and Laurel. U.S. 12 combined with U.S. 10 from an overlap with U.S. 310 in Laurel northeast to Billings. There I-90 shifts eastward to Hardin, while Interstate 94 was built in place of U.S. 10/12 along the Yellowstone River northeast to Fosyth and Miles City. U.S. 12 branches east from Miles City to Baker. I-94 continues in place of U.S. 10 northeast to Terry and Glendive, then east to Wibaux and Beach, North Dakota.

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Additionally U.S. 10A was designated southeast from Cabinet, Idaho to Plains, Paradise and alongside U.S. 93 from Ravalli south to U.S. 10 ahead of Missoula. Within Idaho U.S. 10 ALT followed U.S. 95 south from Sandpoint to U.S. 10 at Coeur D'Alene. The American Association of State Highway Officials (AASHO) approved a joint application from both states to delete U.S. 10 Alternate on October 14, 1967. U.S. 10A east from Sandpoint became part of Multi State Highway 200.

U.S. 10S was replaced by Interstate 90 south from Garrison to Deer Lodge and Butte. The two routes diverged between Butte and Whitehall, which is now Montana State Highway 2. U.S. 10N was replaced by an extension of U.S. 12 west from Townsend, and U.S. 287 between Helena and U.S. 10/10S near Three Forks.

A second U.S. 10A formed a loop south from U.S. 10 at Drummond to U.S. 10S east of Anaconda. This branch was redesignated Montana State Highway 1. The branches of U.S. 10 Alternate, U.S. 10N and U.S. 10S were the result of local politics, where the cities of Anaconda, Helena and Butte vied to be the main U.S. 10 route between Seattle, Washington and Detroit, Michigan.

The eastern truncation of U.S. 10 first dropped the route between U.S. 95 ALT at Wolf Lodge Bay, Idaho to U.S. 93 west of Missoula. This was approved by the American Association of State Highway and Transportation Officials (AASHTO) on July 6, 1977. U.S. 10 remained west from Missoula due to gaps of Interstate 90 yet to be constructed.

AASHTO approved an application for both the elimination of U.S. 10 within Montana and the deletion of U.S. 10A along the loop to Anaconda on June 10, 1986.

Old Highway 10 - East

Old Highway 10 provides an alternate route to Interstate 94 northeast from Powder River Road seven miles to the town of Terry.

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Old Highway 10 and the parallel BNSF Railroad both span the Powder River over Warren through truss bridges.

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The Powder River Bridge along Old Highway 10 was built in 1945.

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Old Highway 10 - East

The Powder River Bridge was added to the National Register of Historic Places on January 4, 2010 (Baughn, 2022).

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Supporting a 25.9 foot wide roadway, the Powder River Bridge measures 635.9 feet in length (Baughn, 2022).

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The adjacent BNSF Railway bridge across the Powder River was originally built in 1921. The outer deck girders were added in 1925 (Baughn, 2021).

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Powder River Road stems 0.54 miles east from Old Highway 10 to the modified diamond interchange with Interstate 94 at Exit 169.

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Page Updated Thursday January 22, 2026.