Mont. Code Ann. § 7-14-101

The highway authorities of the counties, incorporated cities, and towns may, respectively or in cooperation with each other or the state, acquire private or public property and property rights for controlled-access highways or controlled-access facilities and service roads. The property rights may include rights of access, air, view, and light. The property rights may be acquired by gift, devise, purchase, or condemnation in the manner provided in Title 60, chapter 4, part 1, and Title 70, chapter 30.