SDCL § 5-1-10: Public survey records maintained--Access of United States to records.

The state archivist shall receive and safely keep in his office as public records of this state all field notes, maps, plats of surveys, mineral survey notes, homestead survey notes, records, or other papers relating to the public survey of this state, whenever the same shall be turned over to the state in pursuance of law. The United States shall at all times have free access thereto for the purpose of taking abstracts therefrom and making copies thereof.