65 ILCS 20/21-2
This article shall not be in force in the city of Chicago until the question of its adoption shall first have been submitted to the electors of such city and approved by a majority of those voting on the question. The city council of the city of Chicago, by ordinance passed at least thirty days prior to the submission of the question, may direct that the question of the adoption of this Article in place of Article XII of "An Act to provide for the incorporation of cities and villages", approved April 10, 1872, as amended, by the city of Chicago be submitted to popular vote at any general, city, or special election in and for the entire city. The city clerk of the city of Chicago shall promptly certify the passage of such ordinance to the proper election officials, and it shall thereupon be the duty of such election officials to submit the question of the adoption of this article by the city of Chicago, to popular vote.
65 ILCS 20/21-2