Reagan Washington National Airport (DCA) is one of three major airports serving the Baltimore-Washington, DC, metropolitan area, and the closest airport to the nation's capital. It is located just three miles from downtown DC. In total, 11 airlines operate at DCA including US Airways (which has designated DCA as a hub), Air Canada Express, American Airlines, Delta Air Lines, JetBlue Airways, Southwest Airlines and United Airlines. By law, flights to and from Washington National Airport can only be to destinations within 1,250 miles of DCA. However, a total of 20 flights daily can be to destinations that exceed this perimeter.