Chicago (IPA: /ʃɪˈkɑːgoʊ/) is the largest city in the state of Illinois, the largest in the Miwest, and, with a population of nearly 3 million people located almost entirely in Cook County (a portion of the city's O'Hare International Airport overlaps into DuPage County), is the third-most populous city in the United States. The Chicago metropolitan area (commonly referred to as Chicagoland) has a population of over 9.7 million people in Illinois, Wisconsin and Indiana, making it also the third largest metropolitan area in the U.S. Adjacent to Lake Michigan, it is the largest city located on the Great Lakes and among the world's twenty-five largest urban areas by population. Chicago has been classified as an alpha world city for its worldwide economic and cultural influence.