65 ILCS 5/8-4.1-11
A municipality may pledge, as security for the payment of its Bonds, (a) revenues derived from the operation of any utility system or revenue producing enterprise; (b) moneys deposited or to be deposited in any special fund of the municipality; (c) grants or other revenues expected to be received by the municipality from the state or federal government; (d) special assessments to be collected with respect to a local improvement financed with the proceeds of Bonds; or (e) payments to be made by another unit of local government pursuant to a service agreement with the municipality.
Any such pledge made by a municipality shall be valid and binding from the time such pledge is made. The revenues, moneys and other funds so pledged and thereafter received by the municipality shall immediately be subject to the lien of such pledge without any physical delivery thereof or further act; and, subject only to the provisions of prior agreements, the lien of such pledge shall be valid and binding as against all parties having claims of any kind in trust, contract or otherwise against the municipality irrespective of whether such parties have notice thereof. No ordinance, resolution, trust agreement or other instrument by which such pledge is created need be filed or recorded; except in the records of the municipality.
65 ILCS 5/8-4.1-11