65 ILCS 5/7-2-20
If the decision at the election under Section 7-2-1 is in favor of the commission form of municipal government, the united city shall be governed, after the first election held in compliance with Section 7-2-7, by a council, consisting of a mayor and a board of 4 commissioners. One commissioner shall be elected by the electors in each borough. If there are less than 4 boroughs, the remainder of the commissioners shall be elected by the electors of the united city. The nomination petitions of the candidates for the commissioners who are to be elected by the electors in a particular borough shall be signed only by electors of that particular borough. In other respects the nomination and election of officers shall be conducted in compliance with Sections 4-3-1 through 4-3-18. Likewise the tenure of office shall be the same as that provided in Section 4-3-4.
65 ILCS 5/7-2-20