65 ILCS 5/6-3-7

Ward division and election of alderpersons - validation. If, after a census is officially published, any city is divided into a greater or lesser number of wards and has elected a greater or lesser number of alderpersons than the city is entitled, nevertheless such division and election shall be valid and all acts, resolutions and ordinances of the city council of such city, if in other respects in compliance with law, are valid.