Bigger cities like Chicago are “home rule” units, meaning they can zone and tax.
A County which has a chief executive officer elected by the electors of the county and any municipality which has a population of more than 25,000 are home rule units. Other municipalities may elect by referendum to become home rule units. Except as limited by this Section, a home rule unit may exercise any power and perform any function pertaining to its government and affairs including, but not limited to, the power to regulate for the protection of the public health, safety, morals and welfare; to license; to tax; and to incur debt.ILL.CONST. art. VII, §6.