2010.01.04 Chicago, Illinois USA. Chicago is the largest city in both Illinois and the Midwest, and the third most populous city in the United States, with over 2.8 million living within the city limits. Its metropolitan area, commonly named [ссылка], is the 26th most populous[3] in the world, home to an estimated 9.7 million people spread across the U.S. states of Illinois, Wisconsin, and Indiana