Highway 12

Highway 12 crosses the entire state of Montana in an east-west direction. It enters the state over the Lolo Pass and from Missoula east to Garrison, it coincides with Interstate 90. At Garrison, it splits north and crosses Interstate 15 in Helena. Continuing east, it coincides with US 287 until Townsend, when it again becomes independent. Heading northeast through White Sulphur Springs, proceeds easterly through Harlowton, Ryegate, and Roundup before rejoining Interstate 90 near Forsyth. It declares its final independence at Miles City, striking out across lightly populated areas of Custer County and Fallon County, before reaching North Dakota just east of Baker.