Chicago is the largest city in the state of Illinois, the largest in the Midwest and, with a population of nearly 2.9 million people, is the third largest in the United States. Rich in history and renowned for its architecture, Chicago is classified as an alpha world city. It is the anchor of the Chicago metropolitan area, commonly called Chicagoland, which has a population of over.5 million people in Illinois, Wisconsin and Indiana, making it the third largest metropolitan area in the U.S. The City of Chicago is almost entirely located in Cook County, Illinois, with a small portion in DuPage County, while the metropolitan area extends over several counties. Chicago apartments for rent comparison page shows most up to date rent information on Chicago apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.