Chicago's two airports showed a small growth in flights last year, according to preliminary data released on Tuesday.
Air traffic at O'Hare International Airport increased 0.6 percent, while flights at Chicago Midway International Airport grew by 0.9 percent, the Federal Aviation Administration reported.
Atlanta Hartsfield-Jackson International Airport retained its ranking as the busiest U.S. airport, although its total flights decreased by 2 percent last year compared to 2012, the FAA said.
Atlanta handled 911,074 flights in 2013, the FAA said.
O'Hare, which opened a second new runway in October, accommodated 883,287 flights last year.
O'Hare reduced the gap with Atlanta last year, actually serving more flights in July through October, monthly figures show.
The difference in flights between Atlanta and O'Hare in 2012 was 51,990. It was reduced last year to 27,787.
Midway, which serves as a hub for Southwest Airlines, handled 252,126 flights in 2013, the data show.Copyright © 2015, CT Now