DALLAS (AP) -- Southwest Airlines Co. is expanding beyond the continental 48 states with new flights to San Juan, Puerto Rico, as it converts AirTran routes to the Southwest name.
On Sunday Southwest launched service to San Juan and took over AirTran Airways operations in four other cities: Charlotte, N.C.; Flint, Mich.; Portland, Maine; and Rochester, N.Y.
Dallas-based Southwest bought AirTran in 2011.
It's the first time that Southwest has opened new service in five cities on the same day. Southwest carries more U.S. passengers than any airline, although United, Delta and American are bigger when international and domestic traffic are counted.
The last AirTran flights in Charlotte, Flint, Portland and Rochester took off on Saturday. AirTran will continue to fly between San Juan and Baltimore, Atlanta and Fort Lauderdale, Fla. The Fort Lauderdale flights will switch to the Southwest name on Sept. 29.
Southwest executive vice president Ron Ricks said the Puerto Rico flights prove "that our ongoing integration of AirTran remains on track as we're making tremendous progress."
Shares of Southwest fell 20 cents to $12.95 in afternoon trading amid a broader market decline.