65 ILCS 5/3.1-40-40
The passage of all ordinances for whatever purpose, and of any resolution or motion (i) to create any liability against a city or (ii) for the expenditure or appropriation of its money shall require the concurrence of a majority of all members then holding office on the city council, including the mayor, unless otherwise expressly provided by this Code or any other Act governing the passage of any ordinance, resolution, or motion. Where the council consists of an odd number of alderpersons , however, the vote of the majority of the alderpersons shall be sufficient to pass an ordinance. The passage of an ordinance, resolution, or motion to sell any school property shall require the concurrence of three-fourths of all alderpersons then holding office. The yeas and nays shall be taken upon the question of the passage of the designated ordinances, resolutions, or motions and recorded in the journal of the city council. In addition, the corporate authorities at any meeting may by unanimous consent take a single vote by yeas and nays on the several questions of the passage of any 2 or more of the designated ordinances, orders, resolutions, or motions placed together for voting purposes in a single group. The single vote shall be entered separately in the journal under the designation "omnibus vote", and in that event the clerk may enter the words "omnibus vote" or "consent agenda" in the journal in each case instead of entering the names of the members of city council voting "yea" and those voting "nay" on the passage of each of the designated ordinances, orders, resolutions, and motions included in the omnibus group or consent agenda. The taking of a single or omnibus vote and the entries of the words "omnibus vote" or "consent agenda" in the journal shall be a sufficient compliance with the requirements of this Section to all intents and purposes and with like effect as if the vote in each case had been taken separately by yeas and nays on the question of the passage of each ordinance, order, resolution, and motion included in the omnibus group and separately recorded in the journal. Likewise, the yeas and nays shall be taken upon the question of the passage of any other resolution or motion at the request of any alderperson and shall be recorded in the journal.
65 ILCS 5/3.1-40-40