Wis. Stat. § 114.151: Union airports and spaceports.

All powers conferred upon any county, city, village or town by ss. 114.11 to 114.15, relating to the acquisition, establishment, construction, ownership, control, lease, equipment, improvement, maintenance, operation and regulation of airports or landing fields, or spaceports or spacecraft launch or landing areas, may be exercised by any 2 or more municipalities in the establishment, acquisition, equipment and operation of joint airports or landing fields, or spaceports or spacecraft launch or landing areas. The governing body of any county, city, village or town participating in the ownership or operation of a joint airport or spaceport as provided in this section may by resolution withdraw from such joint operation or control and may relinquish its interest in the airport or spaceport.