605 ILCS 5/5-603
For the purpose of providing funds to pay the expenses for engineering and right-of-way costs, utility relocations and its proportionate share of construction or maintenance of highways in the federal aid network or county highway network and costs incurred incident to transportation planning studies conducted in cooperation, and by formal agreement, with the Department of Transportation or its predecessor, the Department of Public Works and Buildings and the designated authority of the United States Government the county board except in counties having a population in excess of 1,000,000 inhabitants has the power to levy an annual tax to be known as the matching tax. Such tax shall be in addition to the maximum of all other county taxes which the county is now or may hereafter be authorized by statute to levy upon the aggregate valuation of all taxable property within the county. Such matching tax shall not be extended at a rate exceeding .05% of the value of all taxable property within the county, as equalized or assessed by the Department of Revenue. On ascertaining the rate per cent that will produce the amount of any tax levied in any such county under this section, the county clerk shall not add to such tax or rate any sum or amount to cover the loss or cost of collecting such tax. All moneys derived from the matching tax shall be placed in a separate fund to be known as the matching fund and shall be used for no other purposes. The county board shall from time to time adopt resolutions appropriating matching funds for specific federal aid projects and motor fuel tax sections or for transportation planning studies conducted in cooperation, and by formal agreement, with the Department of Transportation or its predecessor, the Department of Public Works and Buildings and the designated authority of the United States Government and no moneys shall be disbursed from this fund unless so appropriated by the county board. After the end of the fiscal year, if there is still an unappropriated balance it shall operate to reduce, in like amount, any subsequent levy.
605 ILCS 5/5-603