U.S. airlines carried 1.9 percent more domestic passengers and 5.9 percent more international passengers in the full year 2010 than in 2009, said the Transportation Department.

However, the number of passengers in 2010 still dropped 3.1 percent from 2008' s 743.3 million.

For the December 2010, U.S. airlines carried 58.6 million scheduled domestic and international passengers, increasing 2.9 percent from the same month of 2009.

Delta Air Lines, following its merger with Northwest Airlines, carried more total system passengers in 2010 than any other U.S. airline for the first time since 2001, reaching 110.925 million. Southwest carried most domestic passengers in 2010 for the seventh consecutive year. Delta carried more international passengers in 2010 than any other U.S. carrier after American had carried the most for 20 consecutive years, according to the data.

The gross output of airline system once accounted for 0.95 percent of U.S. GDP. But this proportion fell to 0.76 percent after the "9.11" plane crash took place. With suffering from great economic crisis, the U.S. airline industry experienced another sharp decline in flight demand. However, U.S. airline system traffic has been gradually peaking up from the beginning of 2010.