65 ILCS 5/11-147-2

Any contract specified in Section 11-147-1 may be made by the authority of an ordinance or resolution passed by the proper legislative authority of the municipality, sanitary district, drainage district, or other municipal corporation proposing the contract, and shall be assented to by an ordinance or resolution passed by the proper legislative authority of the municipality, sanitary district, drainage district, or other municipal corporation assenting to the contract. When made and assented to by the proper legislative authorities of the municipal corporations who are parties thereto, the contract shall be in all respects valid and binding.