Mich. Comp. Laws § 252.304

Sec. 4. This act regulates and controls the size, lighting, and spacing of signs and sign structures in adjacent areas and occupies the whole field of that regulation and control except for the following: (a) A county, city, village, township, or charter township may enact ordinances to regulate and control the operation, size, lighting, and spacing of signs and sign structures but shall not permit a sign or sign structure that is otherwise prohibited by this act or require or cause the removal of lawfully erected signs or sign structures subject to this act without the payment of just compensation. A sign owner shall apply for an annual permit pursuant to section 6 for each sign to be maintained or to be erected within that county, city, village, charter township, or township. A sign erected or maintained within that county, city, village, township, or charter township shall also comply with all applicable provisions of this act. An ordinance or code adopted by a county, city, village, township, or charter township that regulates the operation, size, lighting, or spacing of signs and sign structures and that is more stringent than the laws of this state is not made void by this act. (b) A county, city, village, charter township, or township vested by law with authority to enact zoning codes has full authority under its own zoning codes or ordinances to establish commercial or industrial areas and the actions of a county, city, village, charter township, or township in so doing shall be accepted for the purposes of this act. However, except as provided in subdivision (a), zoning that is not part of a comprehensive zoning plan and is taken primarily to permit outdoor advertising structures shall not be accepted for purposes of this act. A zone in which limited commercial or industrial activities are permitted as incidental to other primary land uses is not a commercial or industrial zone for outdoor advertising control purposes. (c) An ordinance or code of a city, village, township, or charter township that existed on March 31, 1972 and that prohibits signs or sign structures is not made void by this act. (d) A county ordinance that regulates and controls the size, lighting, and spacing of signs and sign structures shall only apply in a township within the county if the township has not enacted an ordinance to regulate and control the size, lighting, and spacing of signs and sign structures. (e) A county, on its own initiative or at the request of a city, village, township, or charter township within that county, may prepare a model ordinance as described in subdivision (a). A city, village, township, or charter township within that county may adopt the model ordinance.