Mont. Code § 22-3-101
The historical society of Montana, originally organized under the provisions of an act of the legislative assembly of the territory of Montana entitled "An Act to Incorporate the Historical Society of Montana", approved February 2, 1865, and thereafter made to become the historical society of the state of Montana by an act approved March 4, 1891, entitled "An Act Concerning the Historical Society for the State of Montana and Making an Appropriation Therefor" and by "An Act to Perpetuate the Historical Society of the State of Montana", approved March 1, 1949, is hereby continued and perpetuated as the Montana historical society and as such constitutes an agency of state government for the use, learning, culture, and enjoyment of the citizens of the state and for the acquisition, preservation, and protection of historical records, art, archival, and museum objects, historical places, sites, and monuments and the custody, maintenance, and operation of the historical library, museums, art galleries, and historical places, sites, and monuments.
§ 22-3-101, MCA