10 ILCS 5/2A-1.3
On December 1, 1980 and on December 1 of each even-numbered year the State Board of Elections shall have prepared and published an official State calendar of elections listing the elections to be held during that year and the following year, the election dates, and the offices to be on the ballot at each such election and any functional dates or other information relevant to the conduct of elections. The official calendar shall include all offices in the State.
The official State Calendar shall comply with the schedule of elections established in this Article 2A. The official calendar may be amended from time to time by the Board by adoption and publication of modifications or additions or by adoption and publication of a revised official calendar.
On December 1, 1981 and each odd-numbered year thereafter the Board shall have prepared and published a revised official calendar if any modifications or additions were made by separate publication after the initial adoption of the official calendar for that biennium.
10 ILCS 5/2A-1.3