ATLANTA, Georgia (AP) -- Hartsfield-Jackson Atlanta International Airport ranked as the nation's busiest in terms of flights for a second year in a row last year, according to government data released Thursday.

The Atlanta airport logged 976,307 flights in 2006, down 0.4 percent from its 980,386 flights in 2005, the Federal Aviation Administration said. Flights include takeoffs and landings.

Its rival, Chicago O'Hare International Airport, was listed as second-busiest, with 958,643 flights in 2006. That number was down 1.4 percent from the 972,246 flights it had in 2005, the FAA said.

Atlanta and Chicago have run neck-and-neck in recent years to claim the title of the nation's -- and 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 spokeswoman Sterling Payne cited two reasons for the airport's ranking: "Its capacity and efficiency."

Opening a fifth runaway in May and last year's expansion of international flights by Delta Air Lines Inc. -- which has its primary hub in Atlanta -- both helped the Atlanta airport remain the nation's busiest, Payne said.

O'Hare spokeswoman Wendy Abrams said that flight restrictions imposed by the FAA to limit delays "have limited our ability to land and depart aircraft and, ultimately, meet the demand for air service that continues to grow at our airport."

But the flight caps expire next year and she said city officials are "committed to maintaining Chicago's role as the leading aviation market." An expansion of O'Hare is expected to be finished in 2013.

The third-busiest airport was Dallas-Fort Worth International, with 702,713 flights in 2006, down 2.2 percent from 2005, the FAA said.