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)
NHS	Entire route
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 I-315 / US 89 / MT 200 in Great Falls US 2 in Shelby
North end	Highway 4 at the Sweetgrass-Coutts Border Crossing near Sweetgrass
Location
Country	United States
State	Montana
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) 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 is additionally named as the First Special Service Force Memorial Highway from Helena to the Alberta border, where Alberta Highway 4 continues into Canada retaining that designation.

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