In at least 2 adjacent suburbs to me, chickens are illegal, as well as ducks. In Chicago Downtown there is no restrictions on chickens except possibly the number of them. ( THIS MAKES SENSE COMPLETELY.) There you can see that individual municipalities make their own regulations. If you get enough people together and petition the Mayer and city council to reconsider, then it may happen. If your numbers are small, then you will not be heard.!!! You may need to consult an attorney in your town as to how to go about your petition.
There are towns that have had their laws changed. Some come with restrictions such as number of chickens and no roosters. That makes it at least somewhat easier.
WISHING YOU BEST.