Waukegan () is the most populous city in and the county seat of Lake County, Illinois, United States. It is an industrial suburb about 36 miles (58 km) north of Chicago. As of the 2020 census, its population was 89,321, making it the seventh-most populous city within the Chicago metropolitan area and the 10th-most populous city in Illinois. Unlike many of the surrounding North Shore suburbs, Waukegan is socioeconomically diverse. A significant working-class population and moderately sized middle-class community exist in the community, as well as a number of poorer neighborhoods.