620 ILCS 5/25.02
An adjoining state or political subdivision thereof, if the laws of such state permit, is authorized to acquire, establish, construct, own, control, lease, equip, improve, maintain and operate airports, or restricted landing areas, or other air navigation facilities in this State, subject to all laws, rules and regulations of this State applicable to such aeronautical facilities, but subject to the laws of its own state in all matters relating to financing such projects; provided that prior to the commencement of proceedings for the acquisition or establishment of any such airport, restricted landing area or other navigation facility, approval of such acquisition or establishment has been granted by the Illinois Secretary of Transportation.
620 ILCS 5/25.02