Mont. Code § 7-5-2504
Whenever a petition signed by freeholders owning at least two-thirds of the property fronting on any street of any unincorporated townsite in this state shall be presented to the board of county commissioners of the county in which such townsite is situated praying said board to vacate any park, boulevard, or other public place bordering on said street and the adjoining property and not used for road or highway purposes, which park, boulevard, or public place has been dedicated to public use, such board shall hear said petition, and if in its judgment it appears to be for the best interests of the public that such petition be granted, it shall, by order of the board duly entered upon its minutes, declare such park, boulevard, or public place vacated. Thereupon the land included therein shall attach to and become part of the adjoining lots of said townsite, and the title thereto shall pass with conveyance of said lots.
§ 7-5-2504, MCA