Mich. Comp. Laws § 120.5
Any city or township, or any 2 or more whole contiguous cities or townships, or any combination thereof, by resolution of their respective governing bodies, approved by a majority vote of the electors may form a port district. The resolution shall designate the name of the port district and the cities or townships to be included in the port district. The proposition to create the port district shall be submitted at a general or special election held simultaneously in each city or township having indicated its desire to become a part of the port district, and the date of such election shall be set forth in the resolution. The procedures relative to conducting the election shall be as nearly as may be in the same form as provided herein for the formation of a port district coterminous with a county and when not so provided in conformity with the general election laws or the charter of each city. The creation of the port district shall become effective upon the filing with the secretary of state and county clerk of the county in which the cities or townships are located, of certified copies of each resolution, each election notice, and each official canvass of votes showing that in each city or township the proposition was approved by a majority of the electors voting on the proposition.
MCL 120.5