(1) The portion of Montana highway 3 and U.S. highway 12 from Billings to Harlowton via Lavina, proceeding north on U.S. highway 191 to U.S. highway 87, northwest along U.S. highway 87 to Montana highway 200, continuing along Montana highway 200 through the intersection with U.S. highway 89, and along U.S. highway 87/89 to Great Falls is designated as Montana highway 3.
(2) The department shall erect and maintain signs designating Montana highway 3 along the route established in subsection (1) and shall accomplish the signing changes required in this section in accordance with the department's normal sign maintenance and replacement schedule.