Mich. Comp. Laws § 117.7
Said petition shall accurately describe the proposed boundaries of the city, or of the territory to be annexed thereto or detached therefrom, and if the purpose is to incorporate a new city, it shall represent that the territory described contains not less than 2,000 inhabitants and an average of not less than 500 inhabitants per square mile: Provided, That all incorporated villages in which a county seat is located are hereby authorized to incorporate under the provisions of this act as cities of the fifth class, without respect to the population of the territory included therein: Provided further, That any incorporated village having a population of more than 750 and less than 2,000 inhabitants, or any incorporated village lying within more than 1 township in the same county having a population of more than 600 and less than 2,000 inhabitants, or any territory containing a population of more than 750 and less than 2,000 inhabitants and an average of not less than 500 inhabitants per square mile may incorporate under the provisions of this act as cities of the fifth class. Such cities shall constitute but 1 voting precinct except in cities lying within more than 1 county and the mayor thereof, or whenever provided by resolution of the legislative body of any such city, the city attorney, city manager, or city superintendent shall be among the representatives of the city on the board of supervisors of the county or counties: Provided further, Whenever in the process of incorporating a city of the fifth class and adopting a charter therefor, it shall be disclosed by an official census that the population exceeds 2,000 inhabitants, then all proceedings theretofore taken shall be deemed to be for a non fifth class city under this act.
MCL 117.7