Mont. Code Ann. § 23-2-631

23-2-631 . Operation on public roads, streets, and highways. (1) A person may not operate a snowmobile upon a controlled-access highway or facility at any time. Snowmobile operation is permitted on the roadway or shoulder of any public road or highway, state highway, county road, or city street located within the boundaries of any municipality only in the event that:

(a) the street, road, or highway is drifted or covered by snow to the extent that travel on the street, road, or highway by other motor vehicles is impractical or impossible;

(b) the operator has received permission or is otherwise authorized for that travel by the municipality in the case of town or city streets, the board of county commissioners for county roads, or the state highway patrol for all other highways; or

(c) operation has been authorized on municipal streets by a municipal ordinance.

(2) A snowmobile may make a direct crossing of a street or highway whenever the crossing is necessary to get to another authorized area of operation. The crossing must be made at an angle of approximately 90 degrees to the direction of traffic at a place where no obstruction prevents a quick and safe crossing. The snowmobile must make a complete stop before entering upon any part of the traffic way, and the operator shall yield the right-of-way to all oncoming traffic.

(3) A snowmobile may not be operated upon a public street or highway when permitted to do so by this part unless equipped with at least one headlamp and one taillamp, which must be lighted at all times during operation, and unless equipped with a suitable braking device operable by either hand or foot.

(4) (a) Unless operation is otherwise allowed under subsection (4)(b) or (4)(c), the operator of a snowmobile who operates the snowmobile upon a public roadway, street, or highway when allowed to do so under the provisions of this part must have in possession a license to drive a motor vehicle as required by the laws of the state of Montana.

(b) The operator of a snowmobile may operate the snowmobile upon a public roadway, street, or highway when allowed to do so under the provisions of this part if the operator:

(i) has in possession a certificate showing the successful completion of a Montana-approved snowmobile safety education course; and

(ii) is in the physical presence and under the supervision of a person who is 18 years of age or older.

(c) An operator who crosses a street, road, or highway, who operates a snowmobile upon a street, road, or highway that is drifted or covered with snow to the extent that travel on the street, road, or highway by other motor vehicles is impractical or impossible, or who operates a snowmobile in any other areas of the state where operation is lawfully permitted is not required to apply for or possess a driver's license under the laws of the state of Montana.