55 ILCS 5/5-30017
The county board, upon a recommendation from the preservation commission that the proposed landmark or preservation district should be designated, shall review the report and recommendations of the preservation commission. The county board may schedule a public hearing concerning the proposed designation and shall provide notice of any public hearing in the same manner as provided in Section 5-30014 and conduct the public hearing in the same manner as provided in Section 5-30015. The county board after reviewing the report and recommendation shall within 90 days from receipt of the recommendation of the preservation commission take one of the following steps: (1) designate the landmark or preservation district by ordinance; (2) refer the report and recommendation back to the preservation commission with suggestions for revisions and a further report and recommendation stating its reason for such action. Notice of the action of the county board including a copy of the ordinance designating the landmark or preservation district shall be sent by regular mail to each owner of record of a landmark or property within a preservation district and to owners of adjacent and immediately surrounding property affected by the process for the application for, and review of, a certificate of appropriateness. A map showing the location of all designated landmarks and preservation districts shall be published and amended upon each designation. Copies of the map shall be available to the public at the office of the preservation commission and at the same location and in the same manner as any county zoning map.
55 ILCS 5/5-30017