Interstate 15 in Montana

Interstate 15
Interstate 15
First Special Service Force Memorial Highway
	I-15 highlighted in red
Route information
	Maintained by MDT
Length	396.030 mi (637.349 km)
NHS	Entire route
Major junctions
South end	I-15 at the Idaho state line
	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;

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.