55 ILCS 5/5-1014.5
In counties with a population between 700,000 and 3,000,000, (i) each county appropriation ordinance that is passed that includes appropriations for the county or multiple-county health department and (ii) each appropriation ordinance that is passed by a Metropolitan Airport Authority located within the county shall be presented immediately to the county board chairman. If the county board chairman approves the ordinance, he or she shall sign it and it shall become law. The county board chairman may reduce or veto any item of appropriations for the county or multiple-county health department or for a Metropolitan Airport Authority in the ordinance and shall return the item vetoed or reduced with his or her objections to the county board. A copy of the veto shall also be delivered to the body for which the appropriation is intended. Portions of an ordinance not reduced or vetoed shall become law. Any ordinance not so returned by the county board chairman within 30 calendar days after it is presented to him or her shall become law. If, within 30 calendar days after the veto has been delivered to the county board and the body for which the appropriation is intended, the county board restores an item that has been reduced or overrides the veto of an item by a record vote of three-fifths of the members elected, the item shall become law. If a reduced item is not so restored, it shall become law in the reduced amount.
55 ILCS 5/5-1014.5