Interstate 15 is the only north-south interstate highway in Montana. Beginning at the Canadian border crossing at Sweetgrass, it goes south through Shelby and Conrad to Great Falls. From Great Falls, its direction is south and slightly west through Helena and on to Butte. For about 10 miles west of Butte, it coincides with Interstate 90. Going south again, it crosses Deer Lodge Pass, goes through Dillon and finally enters Idaho at the Monida Pass.