Interstate 15 in Montana

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

I‑90 in Butte

I‑115 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

Interstate Highway System

Montana Highways
Secondary

←

MT 13

MT 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

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 continues through the town of Sunburst before becoming Alberta Highway 4 at the Canadian border just north of Sweetgrass^[2]

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

Exit list

County	Location^[3]	mi^[3]	km	Exit	Destinations	Notes
Monida Pass		0.000	0.000	I‑15 continues south towards Idaho Falls
Monida Pass		0.509	0.819	0	S-509 – Monida
Beaverhead		9.544	15.360	9	Snowline (ranch access)
	Lima	15.185	24.438	15	Lima
	Dell	23.832	38.354	23	Dell
		29.609	47.651	29	Kidd
		37.353	60.114	37	Red Rock
		44.454	71.542	44	S-324 west – Clark Canyon Reservoir
		51.199	82.397	51	Dalys	Southbound exit and northbound entrance only
		52.613	84.672	52	Grasshopper Creek
		56.028	90.168	56	Barretts
		59.702	96.081	59	S-278 west / S-222 – Jackson, Wisdom
	Dillon	62.440	100.487	62	I‑15 Bus. north – Dillon
	Dillon	63.813	102.697	63	I‑15 Bus. south / MT 41 – Dillon
		75.046	120.775	74	Apex, Birch Creek
		85.272	137.232	85	Glen
Madison	Melrose	93.188	149.972	93	Melrose
Silver Bow		99.266	159.753	99	Moose Creek Road
		102.515	164.982	102	MT 43 west – Wisdom
		111.271	179.073	111	Feely
		116.361	187.265	116	Buxton
		119.970	193.073	119	Hub Access – Silver Bow
		121.462	195.474	121	I‑90 – Missoula, Butte	South end of I-90 overlap
		122.491	197.130	122	Rocker
	Butte	124.319	200.072	124	I‑115 / I‑15 Bus. / I‑90 Bus. – City Center
		126.343	203.329	126	Montana Street
		127.961	205.933	127	Harrison Avenue	signed as exits 127A and 127B eastbound
		129.498	208.407	129	I‑90 – Billings	North end of I-90 overlap; I-15 numbered as exit
Jefferson		134.061	215.750	134	Woodville
		138.698	223.213	138	Elk Park
		151.226	243.375	151	Bernice
		156.391	251.687	156	Basin
		159.831	257.223	160	High Ore Road
		164.406	264.586	164	MT 69 – Boulder
		175.576	282.562	176	Jefferson City
		181.575	292.217	182	Clancy
		187.161	301.206	187	S-518 (Sec-282) – Montana City
Lewis and Clark	Helena	189.986	305.753	190	South Helena, Nob Hill area
		191.602	308.354	192	I‑15 Bus. north / US 12 / US 287 south – Townsend, Capitol Area	South end of US 287 overlap
		192.772	310.236		I‑15 Bus. south (Cedar Street)
		199.535	321.120	200	S-279 / S-453 (Lincoln Road)
		208.573	335.666	209	Gates of the Mountains
		215.440	346.717	216	Sieben
		218.667	351.910	219	Spring Creek	Northbound exit and southbound entrance
		226.223	364.071	226	S-434 – Wolf Creek
		228.022	366.966	228	US 287 north – Augusta, Choteau	North end of US 287 overlap
		233.698	376.100	234	Craig
Cascade		239.817	385.948	240	Dearborn
		243.533	391.928	244	Canyon Access
		246.807	397.197	247	Hardy Creek
		249.531	401.581	250	Local Access
		254.042	408.841	254	MT 68 – Cascade
		255.555	411.276	256	MT 68 – Cascade
		269.495	433.710	270	S-330 – Ulm
	Great Falls	276.889	445.610	277	Great Falls International Airport
		278.063	447.499	278	I‑15 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
		279.652	450.056	280	I‑15 Bus. south to US 87 north (Central Avenue West)
		281.631	453.241	282	To US 87 north / Northwest Bypass	Southbound exit and northbound entrance
		285.509	459.482	286	Manchester
		289.607	466.077	290	US 89 north / MT 200 west – Missoula, Choteau	North end of US 89/MT 200 overlap
		296.752	477.576	297	Gordon
Teton		301.528	485.262	302	S-431 – Power
		311.672	501.587	313	S-221 / S-379 – Dutton, Choteau
		319.467	514.132	321	Collins Road
Pondera		326.128	524.852	328	S-365 – Brady
		333.507	536.727	335	I‑15 Bus. north (Midway Road) – Conrad
	Conrad	337.358	542.925	339	I‑15 Bus. south – Conrad
		343.245	552.399	345	S-366 (Ledger Road) – Tiber Dam
		346.250	557.235	348	MT 44 (Valier Road)
		350.259	563.687	352	Bullhead Road
Toole		356.788	574.195	358	Golf Course Road, Marias Valley Road
	Shelby	361.350	581.536	363	I‑15 Bus. north / US 2 – Shelby, Cut Bank
		362.601	583.550	364	I‑15 Bus. south – Shelby
		367.118	590.819	369	Bronken Road
		371.114	597.250	373	Potter Road
		377.123	606.921	379	S-215 / S-343 – Kevin, Oilmont
		383.128	616.585	385	Swayze Road
	Sunburst	387.677	623.906	389	S-552 – Sunburst
		391.930	630.750	394	Ranch Access
		395.770	636.930	397	Sweetgrass (S-214)
		396.030	637.349	Canadian border Roadway continues north as Hwy 4
1.000 mi = 1.609 km; 1.000 km = 0.621 mi Concurrency terminus Incomplete access