55 ILCS 5/1-5010
Whenever the court shall order any county seat election under the provisions of this Division, the court shall appoint three resident legal voters of the point to which it is proposed to remove the county seat, for each and every voting place in the city, precinct or township in which the county seat is situated, also to appoint three resident legal voters of the county seat for each and every voting place in the city, precinct or township to which it is proposed to remove the county seat, to sit with the regular judges to act as challengers of election at the voting places to which they are respectively assigned, and it shall be their duty to act as such challengers and to challenge any and all persons whom they have good reason to believe are not legal voters at such county seat election, and they shall sit with such judges of election until the close of said election, and during the canvass of the votes at said election. The said challengers, who are thus appointed to act with the regular judges of election, may, if they desire so to do, make an affidavit before any person authorized to administer oaths, setting forth in such affidavit that they have been appointed, as above provided, out of the city, precinct, township or ward where they would otherwise be voters, and that they desire to vote at such county seat election; which affidavit, together with the ballot, shall be sealed up in an envelope and left with one of the judges of election for the precinct, and on the day of election shall be by him presented to the board of election and opened in their presence. The affidavit shall be filed, kept and returned with the ballots for that precinct as other affidavits are, and the ballot shall be numbered and deposited in the ballot box, and the name entered on the poll books the same as other votes are.
55 ILCS 5/1-5010