In March, airline traffic rose 2.4 percent compared to March 2009 to 62.4 million passengers.
Traffic was 7.8 percent higher two years ago, however, the DOT said.
From a year ago, domestic travel rose 2 percent while international travel rose 5.1 percent, the report said.
March traffic showed gains compared to the first three months of 2010, which saw 0.9 percent more seats filled on airlines than the same month a year ago.
From January through March, U.S. airlines carried 164.1 million passengers on both domestic and international flights. While an increase from a year ago, that was 10.1 percent lower than the first three months of 2008, the DOT said.