Chicago Midway International Airport (IATA: MDW, ICAO: KMDW, FAA LID: MDW) is a major commercial airport on the southwest side of Chicago, Illinois, located approximately 12 miles (19 km) from the city's Loop business district, and divided between the city's Clearing and Garfield Ridge communities. Established in 1927, Midway served as Chicago's primary airport until the opening of O'Hare International Airport in 1944. Midway is the second-busiest airport in both the Chicago metropolitan area and the state of Illinois, serving 22,050,489 passengers in 2023. Midway is a base for Southwest Airlines, which carries over 90% of the passengers at the airport. The airport was named in honor of the Battle of Midway. The defunct Midway Airlines, once headquartered at Midway, took its name from the airport. The airfield is located in a square mile bounded by 55th and 63rd Streets, Central and Cicero Avenues.