65 ILCS 5/11-76.2-3
After the conclusion of said public hearing, the corporate authorities of the municipality may by a 3/4 vote of the corporate authorities then holding office authorize the exchange as proposed, or as modified as they may find desirable after the holding of the hearing. In case an exchange is so authorized, the authorization shall be by ordinance, wherein findings shall be made as follows: (1) that the premises to be conveyed by the municipality under such exchange, in the opinion of the city council or board of trustees are no longer needed by the municipality for the public interest; (2) that the premises to be received by the municipality under such exchange will prove useful to the municipality and will be for the public interest; and (3) that the total value of the substitutional premises is approximately equal to or exceeds the value of the premises for which same are being exchanged, as determined by the corporate authorities, taking into consideration the long term best interest of the public.
65 ILCS 5/11-76.2-3