The Dallas-based carrier, which last year acquired AirTran Airways, has gone from a peak of 71 daily nonstops to 20 cities from Philadelphia, to 33 daily nonstops to 12 cities now, said spokesman Paul Flaningan.
Southwest currently has three daily flights to Raleigh-Durham.
With the March 2013 schedule, Southwest will increase the frequency of flights between Philadelphia and Chicago Midway from six daily roundtrips to seven dailies, the carrier said. AirTran will add a new seasonal round-trip between Philadelphia and Tampa Bay.
"Since 2008, and the economy and coming out of the recession, we continue to optimize our flights and we're going to move flights where there's not much demand to areas where we are seeing demand," Flaningan said. "To remain profitable, we've got to fly where there's demand."
Southwest has expanded in some cities, including Atlanta and Denver. US Airways, with an international hub in Philadelphia and 453 daily flights, can make money on routes, where Southwest may not, because it takes passengers from the Philadelphia hub on to many other destinations and do not depend only on traffic beginning and ending journeys in those cities.
For consumers, the advantage of competition is lower fares.
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