The Atlanta airport logged 994,466 flights in 2007, up 1.8 percent from 976,447 flights in 2006, the Federal Aviation Administration said. Flights include takeoffs and landings.
Its Chicago rival, O'Hare International Airport, was listed second busiest, with 935,000 flights in 2007. That number was down 2.4 percent from the 958,643 flights it had in 2006, the FAA said.
Atlanta and Chicago have run neck-and-neck in recent years to claim the title of the nation's -- and therefore, the world's -- busiest airport. Atlanta already claimed to be the world's busiest airport in terms of passengers. The FAA does not maintain passenger statistics.
Atlanta airport officials said Hartsfield-Jackson's increased flights in 2007 came from growing demand for air travel in the metro Atlanta area and efforts by Delta Air Lines Inc. and Air Tran Airways, which both have large air travel hubs at the Hartsfield-Jackson.
"Air Tran's domestic growth strategy is working as is Delta's international strategy, which should help us remain a prominent connecting point," said spokesman Herschel Grangent.
A message seeking comment was left for a Chicago Department of Aviation spokesman.
Dallas-Fort Worth International Airport was ranked third, with 686,711 flights in 2007, down 2.3 percent from 702,722 flights in 2006, the FAA said.