Chicago (pronounced /ʃɪˈkɑˌgoʊ/ or /ʃiˈkɔˌgoʊ/; shi-cah-go or shi-caw-go) is the largest city in the state of Illinois, the largest in the Midwest, and, with a population of nearly 3 million people, is the third-most populous city in the United States. The Chicago metropolitan area (commonly referred to as Chicagoland) has a population of over 9.5 million people in Illinois, Wisconsin and Indiana, making it also the third largest metropolitan area in the US.
Chicago is located in Cook County, Illinois, which, with a population of 5,376,741 (2000), is the second most populous in the US, after Los Angeles County, California.
Founded in 1833 at the site of a portage between the Great Lakes and the Mississippi River watershed, it soon became a transportation hub in North America. Since the Chicago World's Fair of 1893, one organization regards it as one of the ten most influential cities in the world.