O'Hare International Airport is the nation's busiest

Chicago's O'Hare International Airport is once again the busiest air traffic hub in the U.S., at least by one metric.

"When passenger and cargo traffic are combined, congratulations are in order again for Chicago. O'Hare back on top for the first time in a decade," said NBC's Brian Williams.

The metric that gave O'Hare its crown back was flight operations, which the Federal Aviation Administration defines as either a takeoff or a landing on an airport's runways.

O'Hare saw more than 880,000 (881,933) flight operations in 2014, edging out Atlanta's Hartsfield-Jackson International Airport, which took the top spot in 2005.

In third comes Dallas/Ft. Worth, then Los Angeles International and Denver International.

But planes aren't the only thing moving through airports. If you look at the numbers of people traveling, Atlanta is still top dog. (Video via WLS-TV)

Numbers from the Airports Council International show Hartsfield-Jackson drew 72,199,400 passengers in 2014. That's almost 20 million more travelers than at O'Hare, with 52,434,527.

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