65 ILCS 5/2-2-1

Whenever a number of electors of a city equal to 1/8 of the electors of the city voting at the last preceding municipal election petition for the submission of the question whether the city shall incorporate under this Code to a vote of the electors in the city, the municipal clerk shall certify this question for submission to a vote of the electors of the city at an election in accordance with the general election law.