Southwest says it's now the second-busiest carrier at Washington National

Southwest Airlines will add a new route to Florida out of Washington's Reagan National Airport (DCA). That will come Nov. 1, when the carrier adds one daily round-trip flight to Orlando.

The service will give Southwest 17 routes from DCA, popular with travelers for its close-to-downtown location.

Southwest has expanded rapidly from DCA during the past year, largely on the strength of landing rights it acquired from American Airlines.

Washington National is one of the few U.S. airports where access is capacity controlled, meaning carriers must obtain slots to add new service. American agreed to divest some of its slots there to help pave the way for its merger with US Airways. Southwest acquired enough slots from American to allow it to add 27 daily round-trip flights from DCA.

Now that it has put most of those slots to use, Southwest says it has become the second-busiest carrier at DCA as measured by passengers flown. American, whose operations now include merger partner US Airways, is the airport's busiest carrier.

Southwest is by far the busiest carrier at Baltimore/Washington International (BWI), another of the three big airports serving the greater Washington metro area. Washington Dulles is the other.