Chicago Midway International Airport (IATA: MDW, ICAO: KMDW, FAA LID: MDW), typically referred to as Midway Airport, Chicago Midway, or simply Midway, is a major commercial airport on the Southwest side of Chicago, Illinois, located approximately 12 miles (19 km) from the Loop business district. Established in 1927, Midway served as Chicago's primary airport until the opening of O'Hare International Airport in 1955. Today, Midway is one of the busiest airports in the nation, the second-busiest airport in the Chicago metropolitan area and the state of Illinois, and serving 20,844,860 passengers in 2019.[4]