Southwest Airlines Co. said Thursday that it will end service in June to Key West; Jackson, Miss.; and Branson, Mo., because it can’t make money serving the smaller markets.

The changes come as the company works on folding AirTran Airways—which served many smaller cities—into the Southwest brand by the end of 2014. The Dallas-based airline is the nation’s fourth-biggest airline by passenger traffic.

Southwest began serving Jackson in 1997 and converted AirTran service in Key West and Branson to its own planes after it bought AirTran in 2011.

The company said that it would operate full schedules to all three airports until the closures.