(WTVO) — Airports have been busy with holiday travelers.

Close to 2.5 million passengers passed through security checkpoints on Friday, the highest number since the pandemic started. Airports and airlines still remain understaffed thought, as more than 600 flights were canceled nationwide Saturday and more than 3,600 were delayed.

There were more than 40 cancellations at Chicago’s O’Hare International Airport and two at Chicago Midway International Airport.