Chicago Midway International Airport ( IATA : MDW , ICAO : KMDW , FAA LID : MDW ) is a major commercial airport on the southwest side of Chicago , Illinois , located eight miles (13 km) from the Loop . Established in 1927, Midway served as Chicago's primary airport until the opening of O'Hare International Airport in 1955. Today, Midway is the second-largest airport in Chicago metropolitan area and the state of Illinois, serving 22,027,737 passengers in 2018. Traffic is currently dominated by low-cost carrier Southwest Airlines ; Chicago is Southwest's largest focus city . Originally named Chicago Municipal Airport , it was renamed to honor the Battle of Midway . The now-defunct Midway Airlines that once serviced the airport took its name from the airport, not vice versa. The airfield is located in a square mile bounded by 55th and 63rd Streets, and Central and Cicero Avenues . The current terminal complex was completed in 2001. The terminal bridges Cicero Avenue and contains 43 gates with facilities for international passengers. Stevenson Expressway ( I-55 ) and the CTA Orange Line provide freeway and rapid transit access to The Loop .