Interstate 15 in Montana

Interstate 15
First Special Service Force Memorial Highway
I-15 highlighted in red
Route information
Maintained by MDT
Length	396.030 mi[1] (637.349 km)
Major junctions
South end	I-15 at the Idaho state line
Major intersections	I-90 in Butte I-115 in Butte US 287 in Helena US 89 / MT 200 in Great Falls US 2 in Shelby
North end	Hwy 4 at the Sweetgrass-Coutts Border Crossing near Sweetgrass
Location
Counties	Beaverhead, Madison, Silver Bow, Jefferson, Lewis and Clark, Cascade, Teton, Pondera, Toole
Highway system
Interstate Highway System Main Auxiliary Suffixed Business Future Montana Highway System Interstate US State Secondary ← MT 13 → MT 16

In the U.S. state of Montana, Interstate 15 (I-15, additionally named as the First Special Service Force Memorial Highway from Helena to the Alberta, Canada border, where it continues on into Canada retaining that designation) continues onward from Idaho for nearly 400 miles (640 km) through the cities of Butte, Helena, and Great Falls, intersecting with I-90, I-115, and I-315. I-15 reaches its northern terminus at the international border with Alberta, Canada.

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

Route description[]

I-15, 20 miles (32 km) 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 , 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.^[2] 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, I-15 passes through the last town before Canada, Sweet Grass, and then crosses the international border, becoming Alberta Highway 4.^[2]

In 1996, I-15 between Helena and Sweet Grass was renamed the "First Special Service Force Memorial Highway".^[3] It was chosen because it was the route taken in 1942 by the Canadian volunteers to join their American counterparts for training at Fort Harrison.^[3]

Exit list[]

County	Location	mi[1]	km	Exit	Destinations	Notes
Monida Pass		0.000	0.000		I-15 south – Idaho Falls	Continuation into Idaho
		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
	​	44.454	71.542	44	S-324 west – Clark Canyon Reservoir
	​	51.199	82.397	51		Southbound exit and northbound entrance only
	​	52.613	84.672	52	Grasshopper Creek
	​	56.028	90.168	56
	​	59.702	96.081	59	S-278 west / S-222 – Jackson, Wisdom
	Dillon	62.440	100.487	62	I-15 BL north – Dillon
		63.813	102.697	63	I-15 BL south / MT 41 – Dillon
	​	75.046	120.775	74	,
	​	85.272	137.232	85	Glen
Madison	​	93.188	149.972	93	Melrose (I-15 Frontage Road/Camp Creek Road)
Silver Bow	Butte	99.266	159.753	99	Moose Creek Road
		102.515	164.982	102	MT 43 west – Wisdom
		111.271	179.073	111
		116.361	187.265	116
		119.970	193.073	119	Hub Access – Silver Bow
		121.462	195.474	121	I-90 west – Missoula	South end of I-90 overlap; I-90 east exit 219; left exits; left entrance northbound
		122.491	197.130	122	Rocker
		124.319	200.072	124	I-115 east / I-15 BL north / I-90 BL east – City Center	Northbound exit and southbound entrance
		126.343	203.329	126	Montana Street
		127.961	205.933	127	I-15 BL south / I-90 BL west (Harrison Avenue)	Signed as exits 127A and 127B northbound; I-15 Bus./I-90 Bus. not signed northbound
		129.498	208.407	129	I-90 east – Bozeman	North end of I-90 overlap; I-90 west exit 227; left exits; left entrance southbound
Jefferson	​	134.061	215.750	134
	​	138.698	223.213	138
	​	151.226	243.375	151
	​	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 () – Montana City
Lewis and Clark	Helena	189.986	305.753	190	, area
		191.602	308.354	192	I-15 BL north / US 12 / US 287 south – Townsend, Capitol Area	South end of US 287 overlap
		192.772	310.236	193	I-15 BL south (Cedar Street)
		193.468	311.357	194	Custer Avenue
		199.535	321.120	200	S-279 / S-453 (Lincoln Road)
	​	208.573	335.666	209
	​	215.440	346.717	216
	​	218.667	351.910	219		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
	​	243.533	391.928	244	Canyon Access
	​	246.807	397.197	247
	​	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 BL 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 BL 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
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 BL north (Midway Road) – Conrad
	Conrad	337.358	542.925	339	I-15 BL 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 BL north / US 2 – Shelby, Cut Bank
	​	362.601	583.550	364	I-15 BL 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
	Sweet Grass	395.770	636.930	397	Sweetgrass ()
		396.030	637.349	Sweetgrass-Coutts Border Crossing; Canada–United States border
					Hwy 4 north – Lethbridge	Continuation into Alberta
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus       Incomplete access

References[]

External links[]

Route map:

Interstate 15
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