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
Mexico City International Airport are United Airlines, American Airlines, Delta Air Lines and Avianca Holdings. Aeroméxico/Aeroméxico Connect operates the most departures from the airport followed by Interjet, Volaris, and Aeromar. Aeroméxico also operates to the most destinations followed by Interjet. This table lists passengers flights served with a nonstop or direct flight with no change of aircraft carrying passengers originating in Mexico City according to the airlines' published schedules, unless otherwise noted. In addition to the scheduled airlines above, Mexico City airport is used by some further airlines for chartered flights including: As of January 2018, Mexico City airport is served by 19 cargo