Michigan Compiled Laws, Chapter 259. Aviation § 259.621

Sec. 1. Any 2 or more counties, cities, incorporated villages, or townships, or any combination thereof, by resolution of their respective legislative bodies, may join to form an airport authority for the purpose of planning, promoting, acquiring, constructing, improving, enlarging, extending, owning, maintaining, and operating the landing, navigational, and building facilities necessary thereto, either within or without their limits, of 1 or more community airports. A site for the physical facilities of the airport authority shall not be selected without the approval of 2/3 of the total membership of the airport authority board and shall be located within the boundaries of the airport authority.