Mich. Comp. Laws § 123.952

Sec. 2. Any combination of 2 or more counties, cities, townships, or villages may incorporate 1 or more joint authorities for the purpose of acquiring, furnishing, equipping, owning, improving, enlarging, operating, and maintaining buildings, automobile parking lots or structures, recreational facilities, stadiums, and the necessary sites therefor, together with appurtenant properties and facilities necessary or convenient for the effective use thereof, for use for any legitimate public purpose of the incorporating units.