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
London City Airport year could be absorbed by other airports which are currently under capacity. However, this plan was proposed when London City Airport was for sale. In February 2016 the airport was bought by a Canadian-led consortium, making redevelopment less likely. Additionally, the political weight behind air space in the south east would make it less likely still, with the government having approved the controversial expansion of Heathrow Airport, including the third runway. Owing to its proximity to London's Docklands and financial district its main users are business travellers, but the number of leisure destinations served (like Palma de Mallorca, Malaga or