For questions about data related to the city of Chicago, the seat of Cook county, northeastern Illinois, the U.S

Chicago, city, the seat of Cook county, northeastern Illinois, the U.S. With a population of nearly three million, Chicago is the state’s largest and the country’s third most populous city

Chicago, on Lake Michigan in Illinois, is among the largest cities in the U.S. Famed for its bold architecture, it has a skyline punctuated by skyscrapers such as the iconic John Hancock Center, 1,451-ft. Willis Tower (formerly the Sears Tower) and the neo-Gothic Tribune Tower.