Chicago is one of the grand cities of not only the United States, but the world: it's been rated an "alpha world city" by the World Cities Study Group. And that was just for its economic importance--not for its architecture, or its music, or its baseball, or its theater, or even its pizza. Chi-town does everything its own way, and it's famous for just about everything it does.
The Chicago region stretches from below the tip of Lake Michigan northward to the Wisconsin border, and west beyond the Fox River. The Chicago metropolitan area includes such cities as Aurora, Joliet, Napierville, and Skokie; and Kendall County, in the western portion, was the fastest-growing county in the United States for most of this century's first decade.
The Chicago metropolitan area is home to 57 major corporations, and the city has the third largest gross metropolitan product in the nation. It ranks 16th on Union Bank of Switzerland's list of the world's richest cities.