Traveling 598 miles across the Glacier State, U.S. 12 enters Montana from Lolo Pass to the west and exits to the east at Little Missouri National Grassland in North Dakota. Following the West Fork of Lolo Creek, U.S. 12 travels northward from Lolo Pass to Lolo Hot Springs, where the two forks of Lolo Creek come together. U.S. 12 leads east from there along side Lolo Creek to the community of Lolo and the beginning of a 7.5-mile overlap with U.S. 93 north into Missoula.
Once in Missoula, U.S. 12 splits with a Business Route into Downtown while staying east to the University of Montana. Leaving Montana's second largest city, U.S. 12 combines with Interstate 90 for 68 miles to Drummond and Garrison. The US highway parallels the Little Blackfoot River east from I-90 to MacDonald Pass across the General Eisenhower Range, becoming a four-lane highway into Helena.
Once in the capital city, U.S. 12 follows Euclid Avenue east to combine with Business Loop I-15 south along an L-shaped route from the business district to Exit 192 of I-15. U.S. 287 joins U.S. 12 east through East Helena, Townsend and the south end of Canyon Ferry Lake. U.S. 287 continues south from there to Three Forks and I-90 while U.S. 12 resumes eastward 28 miles across the Big Belt Mountains to U.S. 89.
U.S. 12/89 overlap eight miles northward to White Sulphur Springs and another three miles east to their split. U.S. 89 heads into the Little Belt Mountains en route to Great Falls while U.S. 12 winds east to Cherkerboard and Harlowton. Harlowton includes a two-mile overlap with U.S. 191, which runs south to Big Timber and north to Lewiston.
Leaving the high mountains for good, U.S. 12 continues 68 miles east to Shawmut, Ryegate and Roundup, where a short overlap exists with U.S. 87. The US route follows the Musselshell River east from Roundup 36 miles to Rosebud County. Bending back southward, U.S. 12 enters Hammond Valley of the Yellowstone River to merge with Interstate 94 east at Forsyth for a 47-mile concurrence to Miles City.
The final 88 miles of U.S. 12 takes the route east from Exit 141 of I-94 across The Pine Hills to Plevna and Baker. U.S. 12 departs the state west of Marmarth, North Dakota.
U.S. 12 Montana Guides
Historic U.S. 312
Until 1974, U.S. 312 ran south from Miles City along Montana 59 to U.S. 212 at Broadus. The former route shared pavement with both U.S. 10 and 12 west from Miles City to Forsyth, and with U.S. 10 west from Forsyth to Exit 23 of I-94. After the completion of Interstate 94, U.S. 312 followed old U.S. 10 along a Northern Pacific Railroad line west from I-94 & U.S. 10 to Worden and U.S. 87 on the north side of Billings. U.S. 87 carried the route southward to its 1962 end in Billings.
Between 1960 and 1962, U.S. 312 continued west from Billings to Laurel, Cooke City and the Northeast Entrance of Yellowstone National Park. This route was discontinued in favor of a westward extension of U.S. 212.
|Overheads direct motorists into the right lane as U.S. 12 approaches the intersection of Arthur Avenue and South 5th Street. Outbound U.S. 12 travels 5th Street west to Higgins Avenue while Arthur Avenue heads to the University of Montana. 11/24/13|
|U.S. 12 trailblazer directing motorists of the right lane turning to Fifth Street heading outbound from the university. 11/24/13|
|The only standing 1961 spec U.S. 12 shield on Fifth Street. 11/24/13|
|This overhead gantry references the original U.S. 93 and U.S. 12 mainlines on Fifth Street west at Higgins Avenue. U.S. 12 now travels 5th Street west onto Higgins Avenue (U.S. 12 Business north into Downtown) south for Brooks Street. U.S. 93 ties into Brooks about a mile ahead from Stephens Avenue. 05/20/13|
|Approaching U.S. 12 (Brooks Street) along Russell Street north in Missoula. Turns are restricted onto U.S. 12 west from this direction as they are completely from U.S. 12 east to Russell Street. 12/30/12|
|U.S. 93 Business appears at the intersection of Russell Street north with Brooks Street in Missoula. U.S. 12/93 Business overlap for 1.7 miles along Brooks Street between Stephens Avenue to the north and Reserve Street (U.S. 93) to the southwest. 12/30/12|
|South Avenue crossed U.S. 12/93 Business (Brooks Street) at Russell Street in Missoula, forming a six-way intersection originally. The east-west road was altered to become a one-way street flowing outwards from Brooks Street to improve the intersection. Sussex Avenue, one block to the north, carries westbound motorists along South Avenue to U.S. 12/93 Business west for the continuation beyond Brooks Street. 12/30/12|
12/30/12, 05/20/13, 11/24/13 by Billy Fortner
Page Updated 10-25-2013.