U.S. Route 12 in Montana

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U.S. Highway 12

Lewis and Clark Highway
US 12 highlighted in red
Route information
Maintained by MDT
Length597.576 mi[1] (961.705 km)
Lewis and Clark Trail
Major junctions
West end US 12 at the Idaho state line at Lolo Pass
Major intersections
East end US 12 at the North Dakota state line east of Baker
CountryUnited States
CountiesMissoula, Granite, Powell, Lewis and Clark, Broadwater, Meagher, Wheatland, Golden Valley, Musselshell, Rosebud, Custer, Fallon
Highway system
MT 7 MT 13

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[2] despite not being the route followed by Lewis and Clark across the state.

Route description

Logging truck at Lolo Hot Springs

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).[1][3]


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.[4]

Major intersections

Lolo Pass0.0000.000
US 12 west / Lewis and Clark Trail / Nez Perce Trail / Northwest Passage Scenic Byway – Lewiston
Continuation into Idaho
US 93 south / Lewis and Clark Trail / Nez Perce Trail – Hamilton
Western end of US 93 concurrency

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

US 93 Bus. north (Stephens Avenue)
Eastern end of US 93 Bus. concurrency
I-90 BL west (East Broadway Street)
Western end of I-90 BL concurrency

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
45.78473.682107East Missoula
MT 200 east / Lewis and Clark Trail – Bonner, Great Falls
Eastern end of MT 200 concurrency
64.840104.350126Rock Creek RoadRock Creek Road Scenic Byway
69.228111.412130Beavertail Road
Granite76.889123.741138Bearmouth Area
Drummond92.167148.328153 MT 1 – Drummond, PhilipsburgEastbound exit and westbound entrance
To MT 1 – Drummond, Philipsburg
Westbound exit and eastbound entrance
Gold Creek104.725168.539166Gold Creek
I-90 east – Butte
Eastern end of I-90 concurrency; eastbound exit and westbound entrance; westbound exit and eastbound entrance via exit 175
MT 141 north – Helmville
PowellLewis and Clark
county line
140.337225.851MacDonald Pass (Continental Divide)
Lewis and ClarkHelena156.631252.073
I-15 BL north (North Montana Avenue)
Western end of I-15 Bus. concurrency
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
East Helena162.562261.618
S-518 south – Montana City
S-284 north
US 287 south / Lewis and Clark Trail – Three Forks, Bozeman
Eastern end of US 287 concurrency
S-284 north
US 89 south – Livingston
Western end of US 89 concurrency
White Sulphur Springs232.418374.041
S-360 west – Fort Logan
US 89 north – Great Falls
Eastern end of US 89 concurrency
S-294 west – Martinsdale
US 191 south – Big Timber
Western end of US 191 concurrency

US 191 north / MT 3 north / Nez Perce Trail – Lewistown
Eastern end of US 191 concurrency; western end of MT 3 concurrency
S-297 north
Golden ValleyRyegate320.079515.117

S-238 north / S-300 south
MT 3 south / Nez Perce Trail – Lavina, Billings
Eastern end of MT 3 concurrency
352.938567.999 S-381
US 87 south – Billings
Western end of US 87 concurrency
US 87 north – Lewistown
Eastern end of US 87 concurrency
S-310 south – Musselshell
S-500 north
I-94 west – Billings
Western end of I-94 concurrency; exit numbers follow I-94
471.584758.941103 S-446 (Rosebud Creek Road) / S-447 – Rosebud
474.700763.956106Butte Creek Road – Rosebud
Custer493.976794.977126Moon Creek Road
496.490799.023128Local Access
Miles City503.235809.878135
I-94 BL east – Jordan, Miles City
506.013814.349138 MT 59 – Miles City, Broadus
I-94 east – Bismarck

I-94 BL west – Miles City
Eastern end of I-94 concurrency
S-320 north – Ismay
S-494 south
Baker585.139941.690 MT 7 – Wibaux, Ekalaka
US 12 east – Bowman
Continuation into North Dakota
1.000 mi = 1.609 km; 1.000 km = 0.621 mi


  1. ^ a b c Road Inventory and Mapping Section (2013). Montana Road Log (PDF). Helena: Montana Department of Transportation. pp. 11–12, 19–20, 59–62, 143–144, 157–159. Archived from the original (PDF) on January 1, 2020. Retrieved November 27, 2020.
  2. ^ Montana Legislature (1947). "60-1-202: Lewis And Clark Highway". Montana Code Annotated. Title 60, Chapter 1, Part 2.
  3. ^ Montana Department of Transportation (2016). Montana Official Highway Map (Map). 1:633,600. Helena: Montana Department of Transportation.[full citation needed]
  4. ^ [1]

External links

U.S. Route 12
Previous state:
Montana Next state:
North Dakota