WASHINGTON (AP) -- U.S. airlines have been adding jobs for six straight months, though the gains aren't big ones.

The U.S. Department of Transportation said Monday that the nation's passenger airlines had the equivalent of 385,619 full-time workers in May, up 1.1% from May 2013. That's the highest level since September 2012.

Delta, American, US Airways and JetBlue added jobs while United shrank 2.5% and Southwest slipped by 0.3%.

Some smaller low-fare airlines are growing faster than bigger airlines in percentage terms. Spirit Airlines and Allegiant Air increased jobs by nearly 13%.

All the major airlines except United made money in the first quarter on strong travel demand. All are expected to post profits for the second quarter, including United.

The government counts two part-time employees as one full-time worker.

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