Mich. Comp. Laws § 45.5: County lands; sale and conveyance.

Sec. 5.

The board of supervisors of each county, or other public officers having the charge and management of the county lands, may, by their order of record, appoint 1 or more agents to sell any real estate of their county not donated for any special purpose, and all deeds, made on behalf of such county, by such agents under their proper hands and seals, and duly acknowledged by them, shall be sufficient to convey all the right, title, interest and estate which the county may then have in and to the land so conveyed.