10 ILCS 5/17-11
On receipt of his ballot the voter shall forthwith, and without leaving the inclosed space, retire alone, or accompanied by children as provided in Section 17-8, to one of the voting booths so provided and shall prepare his ballot by making in the appropriate margin or place a cross (X) opposite the name of the candidate of his choice for each office to be filled, or by writing in the name of the candidate of his choice in a blank space on said ticket, making a cross (X) opposite thereto; and in case of a question submitted to the vote of the people, by making in the appropriate margin or place a cross (X) against the answer he desires to give. A cross (X) in the square in front of the bracket enclosing the names of a team of candidates for Governor and Lieutenant Governor counts as one vote for each of such candidates. Before leaving the voting booth the voter shall fold his ballot in such manner as to conceal the marks thereon. He shall then vote forthwith in the manner herein provided, except that the number corresponding to the number of the voter on the poll books shall not be indorsed on the back of his ballot. He shall mark and deliver his ballot without undue delay, and shall quit said inclosed space as soon as he has voted; except that immediately after voting, the voter shall be instructed whether the voting equipment, if used, accepted or rejected the ballot or identified the ballot as under-voted for a statewide constitutional office. A voter whose ballot is identified as under-voted may return to the voting booth and complete the voting of that ballot. A voter whose ballot is not accepted by the voting equipment may, upon surrendering the ballot, request and vote another ballot. The voter's surrendered ballot shall be initialed by the election judge and handled as provided in the appropriate Article governing that voting equipment.
No voter shall be allowed to occupy a voting booth already occupied by another, nor remain within said inclosed space more than ten minutes, nor to occupy a voting booth more than five minutes in case all of said voting booths are in use and other voters waiting to occupy the same. No voter not an election officer, shall, after having voted, be allowed to re-enter said inclosed space during said election. No person shall take or remove any ballot from the polling place before the close of the poll. No voter shall vote or offer to vote any ballot except such as he has received from the judges of election in charge of the ballots. Any voter who shall, by accident or mistake, spoil his ballot, may, on returning said spoiled ballot, receive another in place thereof only after the word "spoiled" has been written in ink diagonally across the entire face of the ballot returned by the voter.
Where voting machines or electronic voting systems are used, the provisions of this section may be modified as required or authorized by Article 24, 24A, 24B, or 24C, whichever is applicable, except that the requirements of this Section that (i) the voter must be notified of the voting equipment's acceptance or rejection of the voter's ballot or identification of an under-vote for a statewide constitutional office and (ii) the voter shall have the opportunity to correct an under-vote or surrender the ballot that was not accepted and vote another ballot shall not be modified.
10 ILCS 5/17-11