AirTran launched daily service from John Wayne Airport in Santa Ana, Calif., to Cabo San Lucas and Mexico City on June 3.
Both destinations are served by a daily roundtrip.
Air Tran is a wholly-owned subsidiary of Southwest, and AirTran's ticketing and gates at John Wayne Airport are adjacent to Southwest's.
The incoming flights from Mexico inaugurated the new Customs and Border Protection facilities in Terminal C, marking the first time that passports and customs forms have been checked at John Wayne Airport.