O'Hare International Airport was the nation's busiest airport in terms of air traffic during the first half of 2006, surpassing Atlanta's, according to government statistics released Monday.
Hartsfield-Jackson Atlanta International Airport had the second-most flights from Jan. 1 through June 30, according to the Federal Aviation Administration. In third place was Dallas/Fort Worth International Airport.
The number of flights encompasses both takeoffs and landings, according to the FAA.
Chicago and Atlanta have run neck-and-neck in recent years to claim the title of busiest airport.
O'Hare registered 477,001 flights, down 1.3 percent from last year but still enough lead the list, according to the FAA. Atlanta registered 472,431 flights, down 5 percent.
Chicago officials attribute the modest decrease to an FAA-imposed limit on the number of flights at O'Hare to help relieve congestion there. A major expansion project at O'Hare is scheduled to be completed in 2013.
Atlanta has been affected by airlines cutting down on flights that are not full or near full because of high fuel prices, spokeswoman Felicia Browder said. She also noted that Delta Air Lines Inc., which operates the most flights at the airport, has ramped up its international operations and ramped down its domestic operations.
Atlanta argues that it is consistently the nation's busiest airport in terms of passengers. Passenger statistics are not maintained by the FAA and were not immediately available for the first six months of 2006.
Dallas/Fort Worth airport recorded 348,434 flights through June of this year, down 2.1 percent from the same period last year.
Associated Press Writer Harry R. Weber in Atlanta contributed to this report.