Chicago is in the United States.
Chicago ( [ ʃᵻˈkɑːɡoʊ ] or [ ʃᵻˈkɔːɡoʊ ] ) , officially the City of Chicago , is the third-most populous city in the United States . The Chicago metropolitan area , often referred to as Chicagoland , has nearly 10 million people and is the third-largest in the U.S. Chicago has been called a global architecture capital . Chicago has the third-largest gross metropolitan product in the United States -- about $ 640 billion according to 2015 estimates . United States . The capital is Washington , D.C. , and the largest city is New York City ; nine other major metropolitan areas -- each with at least 4.5 million inhabitants and the largest having more than 13 million people -- are Los Angeles , Chicago , Dallas , Houston , Philadelphia , Miami , Atlanta , Boston , and San Francisco .