Chicago is the most populous city in the U.S. state of Illinois and the third most populous in the United States after New York City and Los Angeles. With a population of 2,746,388 in the 2020 census, it is also the most populous city in the Midwest. As the seat of Cook County (the second-most populous U.S. county), the city is the center of the Chicago metropolitan area, one of the largest in the world.
Chicago is located in northeastern Illinois on the southwestern shores of freshwater Lake Michigan. It is the principal city in the Chicago metropolitan area, situated in both the Midwestern United States and the Great Lakes region. The city rests on a continental divide at the site of the Chicago Portage, connecting the Mississippi River and the Great Lakes watersheds. In addition to it lying beside Lake Michigan, two rivers—the Chicago River in downtown and the Calumet River in the industrial far South Side—flow either entirely or partially through the city.