what state is chicago in
Living in Chicago. Chicago (or) is the third most populous city in the United States. Located in the State of Illinois, the city has approximately 2.7 million residents. Its metropolitan area, also called Chicagoland, is the third-largest in the United States, after New York City and Los Angeles, with an estimated 9.8 million people. Chicago is the county seat of Cook County, though a small portion of the city limits also extend into DuPage County.