Chicago is the largest city in the U.S. state of Illinois, as well as the third-most populous city in the United States. Chicago is known as the "Second City," the "Windy City," the "City of Big Shoulders", "Chi-City,” and "Chi-town." The city is a significant port for both domestic and international trade. Chicago contains the headquarters of numerous corporations and is an important wholesale market for grain, machine tools, produce, fish, and flowers. A resident of Chicago is referred to as a Chicagoan.

Chicago is also home to many professional sports teams: the Chicago Cubs baseball team plays at Wrigley Field; the Chicago White Sox baseball team, at Comiskey Park; the Chicago Bears football team, at Soldier Field; and the Chicago Blackhawks ice hockey and Chicago Bulls basketball teams, at the United Center, a new facility that opened in 1994.