Any county or any municipality within the county may, under the "Intergovernmental Cooperation Act", approved September 11, 1973, as now or hereafter amended, enter into an agreement with other counties or municipalities, or both, to jointly establish and operate an airport and its facilities. The Intergovernmental Agreement shall be effective upon its execution by the corporate authorities of each county or municipality that is a party to the agreement and shall continue in effect until terminated as provided in Section 5 of this Act.
620 ILCS 20/1