Chicago is a city in the state of Illinois and the largest in the Midwest. With its population of over 2.8 million people located almost entirely in Cook County (a small portion of O'Hare International Airport overlaps into DuPage County), Chicago is the third largest city in the United States. The population of Chicago's metropolitan area, which covers several counties, contains over 9.7 million people in Illinois, Wisconsin and Indiana, making it the third largest metropolitan area in the U.S.

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Chicago was incorporated as a city in 1837. Its location at the site of a portage between the Great Lakes and the Mississippi River watershed, aided the city's rapid growth. Today, Chicago is a major transportation hub, as well as the business, financial, and cultural capital of the Midwest. 

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Chicago".