Mont. Code Ann. § 7-14-2110

Each board of county commissioners may in its discretion order the county surveyor, or some other surveyor if the county surveyor is incompetent, to prepare suitable platbooks. Each board shall have recorded in it with the county clerk a full description of each county road, showing each course by bearing and distance, a full and complete map of the road, and a record of all proceedings with reference to the road.