Interstate 15 in Montana

This article is about the section of Interstate 15 in Montana. For the entire route, see Interstate 15.

Interstate 15 marker

Interstate 15
Route information
Maintained by Montana Department of Transportation
Length: 397.50 mi[1] (639.71 km)
Major junctions
South end: I-15 at Idaho state line
  I90 in Butte
I115 in Butte
US 287 in Helena
US 89 in Great Falls
US 2 in Shelby
North end: Hwy 4 at Canadian border near Sweetgrass
Highway system

Montana Highways

MT 13MT 16

In the U.S. state of Montana, Interstate 15 continues onward from Idaho for nearly 400 miles (640 km) through the cities of Butte, Helena and Great Falls, intersecting with Interstate 90, Interstate 115 and Interstate 315. Interstate 15 reaches its northern terminus at the international border with Alberta, Canada.

Interstate 15 joins with I-90 and makes a junction with a short, one-mile (1.6 km) spur route Interstate 115 in Butte.

Route description

Interstate 15, 20 miles south of Dillon, Montana
I-15 (foreground left to right) goes through the city of Great Falls, MT

I-15 crosses into Montana from Idaho just south of Lima Reservoir, before the route continues northwest through farmland and desert. The freeway turns north at Clark Canyon Reservoir, before turning northeast. In the town of Dillon, I-15 passes near Clark's Lookout State Park before beginning to parallel the Big Hole River. The freeway then turns away from the river, continuing northeast along Divide Creek through the desert, before splitting away from the creek and heading north. I-15 eventually merges into I-90 at a trumpet interchange.[2]

I-15 and I-90 run concurrently through the city of Butte, coming first to an interchange with I-115, signed as Business Loop 15 and Business Loop 90. I-15 and I-90 pass through a green area in the middle of the city, before I-15 splits off to the northeast on the eastern end of the town. The freeway goes through the forest and plains north of I-90 before winding along Bison Creek and later the Boulder River. I-15 passes through the town of Basin before leaving the mountains and providing access to Boulder. Paralleling Beavertown Creek, the road winds through the hills before passing through Jefferson City. The freeway continues into Helena, where I-15 intersects US 12 and runs concurrently with US 287 through the outskirts of the city before continuing north through the plains.[2]

I-15 and US 287 continue along Little Prickly Pear Creek before passing through the town of Wolf Creek after several miles. Northeast of there, US 287 continues north, while I-15 runs close to the Missouri River. The freeway provides access to Cascade and then continues through the plains through Ulm before turning northeast into the city of Great Falls. I-315 and US 89 intersect with I-15 at a trumpet interchange, and US 89 continues north and then northwest along I-15 for a few miles before continuing to the west. I-15 continues northwest through farmland before passing near Dutton and Brady, and the city of Conrad. US 2 intersects I-15 in the town of Shelby. The freeway passes through the town of Sunburst, then passes through a final stretch of farmland. Eventually, Interstate 15 passes through the last town before Canada, Sweet Grass, and then crosses the international border, becoming Alberta Highway 4.

From Helena to Sweetgrass at the Canadian border, Interstate 15 is dedicated as a memorial highway to the First Special Service Force.

Exit list

Monida Pass0.0000.000 I-15 continues south towards Idaho Falls
0.5090.8190 S-509 Monida
Beaverhead9.54415.3609Snowline (ranch access)
37.35360.11437Red Rock
44.45471.54244 S-324 west Clark Canyon Reservoir
51.19982.39751DalysSouthbound exit and northbound entrance only
52.61384.67252Grasshopper Creek
59.70296.08159 S-278 west / S-222 Jackson, Wisdom
Dillon62.440100.48762 I15 Bus. north Dillon
63.813102.69763 I15 Bus. south / MT 41 Dillon
75.046120.77574Apex, Birch Creek
Silver Bow99.266159.75399Moose Creek Road
102.515164.982102 MT 43 west Wisdom
119.970193.073119Hub Access Silver Bow
121.462195.474121 I90 west MissoulaSouth end of I-90 overlap; I-90 east exit 219; left exits; left entrance northbound
Butte124.319200.072124 I115 east / I15 Bus. north / I90 Bus. east – City CenterNorthbound exit and southbound entrance
126.343203.329126Montana Street
127.961205.933127 I15 Bus. south / I90 Bus. west (Harrison Avenue)Signed as exits 127A and 127B northbound; I-15 Bus./I-90 Bus. not signed northbound
129.498208.407129 I90 east BillingsNorth end of I-90 overlap; I-90 west exit 227; left exits; left entrance southbound
138.698223.213138Elk Park
159.831257.223160High Ore Road
164.406264.586164 MT 69 Boulder
175.576282.562176Jefferson City
187.161301.206187 S-518 (Sec-282) Montana City
Lewis and ClarkHelena189.986305.753190South Helena, Nob Hill area
191.602308.354192 I15 Bus. north / US 12 / US 287 south Townsend, Capitol AreaSouth end of US 287 overlap
192.772310.236193 I15 Bus. south (Cedar Street)
199.535321.120200 S-279 / S-453 (Lincoln Road)
208.573335.666209Gates of the Mountains
218.667351.910219Spring CreekNorthbound exit and southbound entrance
226.223364.071226 S-434 Wolf Creek
228.022366.966228 US 287 north Augusta, ChoteauNorth end of US 287 overlap
243.533391.928244Canyon Access
246.807397.197247Hardy Creek
249.531401.581250Local Access
254.042408.841254 MT 68 Cascade
255.555411.276256 MT 68 Cascade
269.495433.710270 S-330 Ulm
Great Falls276.889445.610277Great Falls International Airport
278.063447.499278 I15 Bus. north / US 89 south / MT 200 east (10th Avenue South, I-315 east, MT 3 south)South end of US 89/MT 200 overlap
279.652450.056280 I15 Bus. south to US 87 north (Central Avenue West)
281.631453.241282 To US 87 north / Northwest BypassSouthbound exit and northbound entrance
289.607466.077290 US 89 north / MT 200 west Missoula, ChoteauNorth end of US 89/MT 200 overlap
Teton301.528485.262302 S-431 Power
311.672501.587313 S-221 / S-379 Dutton, Choteau
319.467514.132321Collins Road
Pondera326.128524.852328 S-365 Brady
333.507536.727335 I15 Bus. north (Midway Road) Conrad
Conrad337.358542.925339 I15 Bus. south Conrad
343.245552.399345 S-366 (Ledger Road) Tiber Dam
346.250557.235348 MT 44 (Valier Road)
350.259563.687352Bullhead Road
Toole356.788574.195358Golf Course Road, Marias Valley Road
Shelby361.350581.536363 I15 Bus. north / US 2 Shelby, Cut Bank
362.601583.550364 I15 Bus. south Shelby
367.118590.819369Bronken Road
371.114597.250373Potter Road
377.123606.921379 S-215 / S-343 Kevin, Oilmont
383.128616.585385Swayze Road
Sunburst387.677623.906389 S-552 Sunburst
391.930630.750394Ranch Access
395.770636.930397Sweetgrass (S-214)
396.030637.349Canadian border
Roadway continues north as Hwy 4
1.000 mi = 1.609 km; 1.000 km = 0.621 mi


  1. "Route Log- Main Routes of the Eisenhower National System of Interstate and Defense Highways - Table 1". Retrieved 4 October 2014.
  2. 1 2 Google (December 22, 2013). "Interstate 15 in Montana" (Map). Google Maps. Google. Retrieved December 22, 2013.
  3. 1 2 Staff (2011). Montana Road Log (PDF) (Report). Montana Department of Transportation. p. 2-8. Retrieved December 21, 2013.

External links

Route map: Bing / Google

KML is from Wikidata
Interstate 15
Previous state:
Montana Next state:
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