High Quality Content by WIKIPEDIA articles! Lambert–St. Louis International Airport (IATA: STL, ICAO: KSTL, FAA LID: STL) is an international airport serving Greater St. Louis. It is about 10 miles (16 km) northwest of downtown St. Louis in unincorporated St. Louis County between Berkeley and Bridgeton. It is the largest and busiest airport in the state with 255 daily departures to about 90 domestic and international locations. In 2011, nearly 13 million passengers traveled through the airport. The airport serves as a focus city for Southwest Airlines.