35 ILCS 200/9-40
In any county with less than 3,000,000 inhabitants which elects a county assessor under Section 3-45, the county assessor shall, except as provided in Section 5-1108 of the Counties Code, prepare and maintain tax maps, up-to-date lists of property owners' names and addresses, and property record cards for all of the property in the county. Those documents shall be prepared and maintained in accordance with rules and procedures prescribed by the Department. The county assessor also shall procure at regular intervals from the records maintained by the recorder information relating to transfers of property. The county assessor shall not duplicate the work of any fulltime township assessor who maintains up-to-date and complete tax maps, ownership lists and property record cards in accordance with rules and procedures prescribed by the Department, but this shall not preclude the maintenance of duplicate copies of those records in the county assessor's office. This Section does not prohibit the preparation and setting up of a property record system (including appraisals) and property record cards as provided for in other Acts, but the system and records shall not be considered to be assessments nor limit the powers and duties of the assessors under this Code. Systems and records or copies of them set up under such other Acts may be maintained by the county assessor in his or her office. In preparing the original tax maps, lists and property record cards, the county assessor shall consult with the Department. The Department shall furnish to that officer supplies and equipment as may, in its judgment, be necessary to set up the original set of maps, lists and records required by this Section.
35 ILCS 200/9-40