Southwest to land Sunday at New York's LaGuardia

— -- The Dallas-based carrier is launching service at LaGuardia Airport, the kind of heavily congested airport it eschewed for three decades in its dedication to keeping costs low.

It will fly five times a day to Chicago's Midway Airport and three times daily to Thurgood Marshall Baltimore/Washington International Airport. Connecting to those airports, Southwest's second- and fourth-biggest points of operation, will give nearly all of its 102 million yearly passengers one-stop access to New York City.

Southwest, which has about 3,300 flights a day now, is still the industry's leading fare price discounter and is the largest U.S. airline in passengers carried.

It has a cost-per-mile advantage of about 20% over conventional network carriers. But its costs have risen as it matured and grew into a 539-plane behemoth with 35,000 workers.

Those rising costs are driving it to serve more major markets and more of the kind of high-cost airports it used to shun as it seeks a bigger share of the business travel market.

In recent years it has moved into such big city airports at Philadelphia, Denver and San Francisco and has been trimming service in secondary markets.

This year, in addition to LaGuardia, its 66th airport, Southwest has launched service at Minneapolis-St. Paul Airport and plans to begin serving Boston's Logan Airport on Aug. 16. It will begin serving Milwaukee in November.