Chicago has been known as the last major city in the United States that still mandates lead and oakum cast iron systems in buildings. No-hub fittings have never been allowed in the Chicago Plumbing Code. What is interesting is that caulking tools used to make lead and oakum joints are normally found in the plumbing museum.
If you mention to plumbing professionals in other parts of the country — or world — that all DWV systems in Chicago are installed in cast iron with lead and oakum joints, they laugh at you. They think it is a joke. But it is not. Lead and oakum joints have been a mainstay since indoor plumbing was installed in Chicago.