The boundaries of the 3 assessment districts are as follows: (i) the first assessment district shall be that portion of the county located within the boundaries of a municipality with 1,000,000 or more inhabitants, (ii) the second assessment district shall be that portion of the county that lies north of State Route 64 (North Avenue) and outside the boundaries of a municipality with 1,000,000 or more inhabitants, and (iii) the third assessment district shall be that portion of the county that lies south of State Route 64 (North Avenue) and outside the boundaries of a municipality with 1,000,000 or more inhabitants.
35 ILCS 200/9-220