Northern Virginia from the older National Airport (a focus city for American Airlines) are restricted for distance, frequency, and flight paths due to the proximity to federal facilities, Dulles is the region's second busiest airport in both passenger loadings and aircraft movements, and the sixteenth-busiest airport in the United States by takeoffs and landings in 2007. Dulles is the region's primary international gateway, serves as a hub for United Airlines, and has recently improved its low-cost carrier offerings with the addition of multiple flights by Southwest and JetBlue. Commuters are served by the Washington Metro subway and the Virginia Railway Express, a
Washington Dulles International Airport to a limited access highway, with the interchanges financed through a property tax surcharge on nearby business properties. The Dulles Toll Road has been extended to the west to Leesburg as the Dulles Greenway. Fairfax Connector routes 981 and 983 serve Dulles, connecting to the Herndon–Monroe park & ride lot in Herndon, the Reston Town Center transit in Reston, the Wiehle – Reston East Metro station, and the Steven F. Udvar-Hazy Center Air and Space Museum. The "Express" 5A Metrobus route operates service to the airport. The bus stops at the Herndon–Monroe park & ride lot in Herndon and the