75 ILCS 5/3-2
The corporate authorities of any city of over 500,000 population may levy a tax for library maintenance and operation for the years 1970 and 1971 of not to exceed .10% and for the years thereafter of not to exceed .12% of the value of all taxable property in the city, as equalized or assessed by the Department of Revenue. The corporate authorities may also levy an additional tax of .02% of the value of all the taxable property in the city, as equalized or assessed by the Department of Revenue, for the purchase of sites and buildings, for the construction and equipment of buildings, for the rental of buildings required for library purposes, and for maintenance, repairs and alterations of library buildings and equipment. If, however, the corporate authorities desire to levy a tax for any year after 1971 in excess of .12% but not in excess of .20% of value for library maintenance and operation, the corporate authorities may, by ordinance, stating the tax rate desired, cause a proposition for an assent thereto to be submitted to the voters of the city at a general election to be held in November of even numbered years. The proposition shall be in substantially the form prescribed in Section 3-3. If a majority of the votes cast upon the proposition are in favor thereof, the corporate authorities may thereafter levy annually a tax for library maintenance and operation at the authorized increased rate. Any tax levied pursuant to Section 3-9 shall be disregarded in applying the provision of this Section.
75 ILCS 5/3-2