10 ILCS 5/2A-24
A County Commissioner shall be elected at each general election in counties not under township organization to succeed each incumbent Commissioner whose term expires before the following general election.
The Board of County Commissioners, at least 30 days before the first day for filing nomination petitions preceding each primary election in which 2 Commissioners are to be elected, may provide by resolution that candidates for such position shall each file nomination papers for and be nominated for and elected to a specific office. The resolution shall designate the positions to be filled as follows: Position A is the position now held (or vacated) by ........... (Name of one incumbent or most recent Commissioner) and position B is the position now held (or vacated) by .......... (Name of the other incumbent or most recent Commissioner).
10 ILCS 5/2A-24