DALLAS -- Southwest Airlines Co. trimmed its schedule Tuesday, eliminating 32 roundtrip flights and adding 19 new ones starting next May.

For Idaho, the changes mean daily flights between Boise and Portland, Ore., will be cut to two each way, down from three.

The Dallas-based carrier released its schedule for May 9 through June 26.

Chief Executive Gary Kelly said the schedule attempted to maximize the use of aircraft on the best routes.

Among markets adding new nonstop flights in May are Nashville, Tenn., and Oakland, Calif., and Nashville and Seattle.

Southwest serves 64 U.S. cities and plans to add flights to Minneapolis in March. The airline carries more domestic passengers than any other, on more than 3,300 daily flights.