70 ILCS 1205/5-4
When a park district lies in 2 or more counties, the board shall ascertain the total amount of all taxable property situated within the district in each county as the property is equalized or assessed by the Department of Revenue for the current year and shall certify the amount of taxable property in each county within the district to the county clerk of the county wherein the greater portion of the district, in area, lies. That county clerk shall ascertain the rate per cent which, upon the total valuation of all property subject to taxation within the district, will produce a net amount not less than the total amount directed to be levied. As soon as such rate per cent is ascertained, that clerk shall certify the rate per cent to the county clerks of each other county wherein a portion of the district is situated. The county clerks of the respective counties shall then extend the tax in a separate column upon the books of the collector of state and county taxes for his county against all taxable property in his county situated within the limits of the park district.
70 ILCS 1205/5-4