U.S. Route 12 in Montana
# U.S. Route 12 in Montana

U.S. Highway 12 (US 12) is an east–west United States Numbered Highway in the state of Montana. It extends approximately 597.576 miles (961.705 km) from the Idaho state line east to the North Dakota state line, the greatest distance that US 12 traverses through any state.

US 12 in Montana has been defined as the Lewis and Clark Highway despite not being the route followed by Lewis and Clark across the state.

## Route description

US 12 enters Montana at Lolo Pass, seven miles (11 km) southwest of Lolo Hot Springs in Lolo National Forest. After passing Lolo Peak to the south and traveling east for 33 miles (53 km), it meets with US 93 at Lolo and continues running concurrently northeast for 7.5 miles (12.1 km), where US 93 heads due north on Reserve Street, toward Kalispell and Glacier National Park. US 12 continues northeasterly through Missoula's downtown, eventually meeting Interstate 90 (I-90). It then overlaps I-90 for 69 miles (111 km), until Garrison, where it heads eastward toward Helena for 48.8 miles (78.5 km). This two-lane section of the trip passes through Avon and Elliston winding through Helena National Forest, over the Continental Divide at MacDonald Pass, and then through Montana's capital city, Helena.

On the east end of Helena, US 12 passes over I-15 at which point it joins US 287 south. US 12 overlaps US 287 and heads southeasterly, toward Townsend for 33.4 miles (53.8 km), where it splits from US 287, which heads south toward the intersection of I-90 near the town of Three Forks. US 12 heads eastward toward White Sulphur Springs for 42.2 miles (67.9 km); the route joins US 89 (which heads south toward Livingston and Yellowstone National Park) for 8.4 miles (13.5 km) before entering White Sulphur Springs and for another three miles (4.8 km) east of town. US 12 continues east for 54.4 miles (87.5 km) to Harlowton where it joins US 191 and share a 1.4-mile (2.3 km) concurrency through town. On the east end of Harlowton, the routes meet with Montana Highway 3 (MT 3), where US 191 and MT 3 share a common alignment and continue north to Lewistown and MT 3 joins US 12. US 12 and MT 3 continue east for 45.2 miles (72.7 km) before MT 3 heads south near Lavina and continues to Billings. US 12 continues east 21.4 miles (34.4 km) until the junction of US 87 and the two routes continue as a 2.1-mile (3.4 km) concurrency through Roundup. US 87 splits north and US 12 continues east on its own for 101 miles (163 km), until the junction with I-94 at Forsyth as a concurrency northeast for 45.8 miles (73.7 km) to Miles City. At the east exit for Miles City, US 12 splits again from I-94 and heads almost directly east to the North Dakota border at a distance of 92.4 miles (148.7 km).

## History

US 12 had a proposal to be routed southwestward from Miles City through Forsyth, Hysham, Billings, Laurel, Rockvale, Red Lodge, and Cooke City, partially on the path of US 212. This path would have also taken the highway into Wyoming, with a second piece in Montana.

## Major intersections

| County | Location | mi | km | Exit | Destinations | Notes |
| - | - | - | - | - | - | - |
| Lolo Pass | Lolo Pass | 0.000 | 0.000 | | US 12 west / Lewis and Clark Trail / Nez Perce Trail / Northwest Passage Scenic Byway – Lewiston | Continuation into Idaho |
| Missoula | Lolo | 32.556 | 52.394 | | US 93 south / Lewis and Clark Trail / Nez Perce Trail – Hamilton | Western end of US 93 concurrency |
| Missoula | Missoula | 40.080 | 64.503 | | US 93 north (South Reserve Street) to I-90 – Kalispell | Eastern end of US 93 concurrency; western terminus of US 93 Bus.; western end of US 93 Bus. concurrency |
| Missoula | Missoula | 41.745 | 67.182 | | US 93 Bus. north (Stephens Avenue) | Eastern end of US 93 Bus. concurrency |
| Missoula | Missoula | 43.806 | 70.499 | | I-90 BL west (East Broadway Street) | Western end of I-90 BL concurrency |
| Missoula | Missoula | 44.159 | 71.067 | 105 | I-90 west / MT 200 west – Coeur d'Alene | Eastern end of I-90 BL concurrency; eastern terminus of I-90 BL; western end of I-90 / MT 200 concurrency; exit numbers follow I-90 |
| Missoula | Missoula | 45.784 | 73.682 | 107 | East Missoula | |
| Missoula | Bonner | 48.999 | 78.856 | 109 | MT 200 east / Lewis and Clark Trail – Bonner, Great Falls | Eastern end of MT 200 concurrency |
| Missoula | Turah | 52.884 | 85.109 | 113 | Turah | |
| Missoula | Clinton | 59.788 | 96.219 | 120 | Clinton | |
| Missoula | ​ | 64.840 | 104.350 | 126 | Rock Creek Road | Rock Creek Road Scenic Byway |
| Missoula | ​ | 69.228 | 111.412 | 130 | Beavertail Road | |
| Granite | ​ | 76.889 | 123.741 | 138 | Bearmouth Area | |
| Granite | Drummond | 92.167 | 148.328 | 153 | MT 1 – Drummond, Philipsburg | Eastbound exit and westbound entrance |
| Granite | Drummond | 93.092 | 149.817 | 154 | To MT 1 – Drummond, Philipsburg | Westbound exit and eastbound entrance |
| Powell | Jens | 101.002 | 162.547 | 162 | Jens | |
| Powell | Gold Creek | 104.725 | 168.539 | 166 | Gold Creek | |
| Powell | Phosphate | 108.692 | 174.923 | 170 | Phosphate | |
| Powell | Garrison | 112.836 | 181.592 | 174 | I-90 east – Butte | Eastern end of I-90 concurrency; eastbound exit and westbound entrance; westbound exit and eastbound entrance via exit 175 |
| Powell | ​ | 125.743 | 202.364 | | MT 141 north – Helmville | |
| Powell–Lewis and Clark county line | ​ | 140.337 | 225.851 | | MacDonald Pass (Continental Divide) | MacDonald Pass (Continental Divide) |
| Lewis and Clark | Helena | 156.631 | 252.073 | | I-15 BL north (North Montana Avenue) | Western end of I-15 Bus. concurrency |
| Lewis and Clark | Helena | 158.241 | 254.664 | | I-15 / US 287 north / Lewis and Clark Trail – Great Falls, Butte | I-15 exit 192; eastern end of I-15 BL concurrency; southern terminus of I-15 BL; western end of US 287 concurrency |
| Lewis and Clark | East Helena | 162.562 | 261.618 | | S-518 south – Montana City | |
| Lewis and Clark | Louisville | 169.468 | 272.732 | | S-284 north | |
| Broadwater | Townsend | 190.311 | 306.276 | | US 287 south / Lewis and Clark Trail – Three Forks, Bozeman | Eastern end of US 287 concurrency |
| Broadwater | ​ | 192.713 | 310.142 | | S-284 north | |
| Meagher | ​ | 223.562 | 359.788 | | US 89 south – Livingston | Western end of US 89 concurrency |
| Meagher | White Sulphur Springs | 232.418 | 374.041 | | S-360 west – Fort Logan | |
| Meagher | ​ | 235.361 | 378.777 | | US 89 north – Great Falls | Eastern end of US 89 concurrency |
| Meagher | ​ | 266.380 | 428.697 | | S-294 west – Martinsdale | |
| Wheatland | Harlowton | 289.790 | 466.372 | | US 191 south – Big Timber | Western end of US 191 concurrency |
| Wheatland | Harlowton | 291.176 | 468.602 | | US 191 north / MT 3 north / Nez Perce Trail – Lewistown | Eastern end of US 191 concurrency; western end of MT 3 concurrency |
| Wheatland | Shawmut | 306.435 | 493.159 | | S-297 north | |
| Golden Valley | Ryegate | 320.079 | 515.117 | | S-238 north / S-300 south | |
| Golden Valley | ​ | 336.354 | 541.309 | | MT 3 south / Nez Perce Trail – Lavina, Billings | Eastern end of MT 3 concurrency |
| Golden Valley | ​ | 352.938 | 567.999 | | S-381 | |
| Musselshell | ​ | 357.720 | 575.695 | | US 87 south – Billings | Western end of US 87 concurrency |
| Musselshell | Roundup | 359.788 | 579.023 | | US 87 north – Lewistown | Eastern end of US 87 concurrency |
| Musselshell | ​ | 382.425 | 615.453 | | S-310 south – Musselshell | |
| Musselshell | ​ | 396.097 | 637.456 | | S-500 north | |
| Rosebud | Forsyth | 461.175 | 742.189 | 93 | I-94 west – Billings | Western end of I-94 concurrency; exit numbers follow I-94 |
| Rosebud | Forsyth | 462.803 | 744.809 | 95 | Forsyth | |
| Rosebud | ​ | 471.584 | 758.941 | 103 | S-446 (Rosebud Creek Road) / S-447 – Rosebud | |
| Rosebud | ​ | 474.700 | 763.956 | 106 | Butte Creek Road – Rosebud | |
| Rosebud | ​ | 485.470 | 781.288 | 117 | Hathaway | |
| Custer | ​ | 493.976 | 794.977 | 126 | Moon Creek Road | |
| Custer | ​ | 496.490 | 799.023 | 128 | Local Access | |
| Custer | Miles City | 503.235 | 809.878 | 135 | I-94 BL east – Jordan, Miles City | |
| Custer | Miles City | 506.013 | 814.349 | 138 | MT 59 – Miles City, Broadus | |
| Custer | ​ | 508.880 | 818.963 | 141 | I-94 east – Bismarck I-94 BL west – Miles City | Eastern end of I-94 concurrency |
| Fallon | ​ | 559.863 | 901.012 | | S-320 north – Ismay | |
| Fallon | Plevna | 572.578 | 921.475 | | S-494 south | |
| Fallon | Baker | 585.139 | 941.690 | | MT 7 – Wibaux, Ekalaka | |
| Fallon | ​ | 597.576 | 961.705 | | US 12 east – Bowman | Continuation into North Dakota |
| 1.000 mi = 1.609 km; 1.000 km = 0.621 mi Concurrency terminus Incomplete access |||||||
