About Chicago

Chicago ( (listen) shih-KAH-goh, locally also shih-KAW-goh) is the most populous city in the U.S. state of Illinois, and the third-most populous in the United States, following New York City and Los Angeles. With a population of 2,746,388 in the 2020 census, it is the most populous city in the Midwestern United States. Chicago, the county seat of Cook County (the second-most populous U.S. county), is the center of the Chicago metropolitan area, one of the largest in the world. On the shore of Lake Michigan, Chicago was incorporated as a city in 1837 near a portage between the Great Lakes and the Mississippi River watershed. It grew rapidly in the mid-19th century; by 1860, Chicago was the youngest U.S. city to exceed a population of 100,000.