Washington, Dec 21 (IANS): US airline system traffic in September shrank from a year ago, authorities said.

US airlines carried 57.4 million domestic and international passengers in September 2012, 1.1 percent fewer than in the same period of 2011, said the Transportation Department. But the number of passengers was still 0.1 percent above that of two years ago in September 2010.

Specifically, there were 1.7 percent fewer domestic passengers and 2.8 percent more international passengers in September than a year ago, reported Xinhua.

Delta Airlines carried more total passengers than any other US airlines in September, reaching 9.39 million. Southwest Airlines carried the most domestic passengers, with 8.70 million. United Airlines took the first place in terms of international passengers, with as many as 1.9112 million.

In the first nine months of this year, US airlines carried 559.2 million passengers in total, up 1.3 percent from the same period of 2011. There were 486.5 million domestic passengers, and 72.7 million international ones.

The US airline industry suffered a sharp decline in flight demand during the latest economic recession. However, the nation's airline traffic has been gradually picking up since early 2010.