Southwest Airlines planes take off from the airline's hub at Dallas Love Field Airport March 12, 2008, in Dallas, Texas.
Southwest Airlines Co. is expanding beyond the continental 48 states with new flights to San Juan, Puerto Rico, as it converts AirTran Airways routes.
Dallas-based Southwest on Sunday launched service to San Juan and took over AirTran operations in four other cities: Charlotte, N.C.; Flint, Mich.; Portland, Maine; and Rochester, N.Y.
Southwest bought AirTran in 2011.
Southwest began flying out of Portland on Sunday for regularly scheduled flights to Baltimore-Washington. The airline is offering three daily nonstop flights between Portland and Baltimore-Washington from Sunday through Friday, and two flights on Saturdays.
AirTran's last flights out of Portland were on Saturday.