The highway extends approximately 38 miles (61 km) to an intersection with Interstate 15 (I-15) at the northern edge of the town of Boulder.

Most of the route follows the Boulder River valley, a scenic and relatively unspoiled rural landscape.

Concurrent with MT 2, it runs parallel to I-90, before intersecting it, and proceeding northward.

Through a scenic and rural area, MT 69 proceeds north as South Main Street as it enters Boulder.

[2][3] The southerly six miles of the current MT 69 follows a former alignment of U.S. Route 10 and parallels Interstate 90; the U.S. 10 designation was deleted in Montana after the completion of the interstate.