605 ILCS 10/24
Except as otherwise provided in any bond resolution, the proceeds derived from the sale of bonds, and all receipts and income derived from tolls, licenses, gifts, donations, concessions, fees, rentals, and all other revenues from whatever source derived, shall, within three days after receipt thereof, be paid to the Treasurer of the State of Illinois, and held by him as a special fund known as the Illinois State Toll Highway Authority Fund, except that the Authority may retain portions of the Illinois State Toll Highway Authority Fund as a locally maintained construction fund revolving account and as a revenue fund revolving account, where authorized by a bond resolution, and as locally maintained change funds, where necessary for the operations of the Authority. The State Treasurer shall be ex officio custodian of such special fund, which fund shall be held, invested and disbursed for the purposes provided herein upon the order of the Authority and in accordance with provisions and covenants of any bond resolution authorizing the issuance of bonds which have not been paid or deemed paid. The interest accruing on said special fund shall be computed and added to the principal thereof every six months. In addition to the special audits prescribed by this Act, the said fund shall also be subject to audit in the same manner as is now, or may hereinafter be, provided for the audit of State funds and accounts. The said special fund shall be protected by a corporate surety bond, executed by the Treasurer, with a surety authorized to do business under the laws of the State of Illinois. The amount of said bond shall be fixed by resolution of the Authority, approved by the Governor, and may be increased or diminished at any time. The premiums on said bond shall be payable from the funds of the Authority. The bond shall be subject to the approval of the Governor and Attorney General of the State of Illinois, and, when so approved, shall be filed in the office of the Secretary of State. Said special fund shall be considered always appropriated for the purposes of disbursements, as provided in this Act, and shall be paid out and disbursed only as provided herein, and shall not, at any time be appropriated or diverted to any other use or purpose.
605 ILCS 10/24