Sunday saw more than 2,100 flights canceled across the U.S. on the final day of the holiday travel season before many Americans return to work for the new year Monday, according to FlightAware. That follows the some 2,700 flights that were canceled on Saturday, which was New Year's Day.

"Weather and heavy seasonal traffic are likely to result in some travel delays in the coming days," an FAA spokeswoman told FOX Business Sunday. "Like the rest of the U.S. population, an increased number of FAA employees have tested positive for COVID-19. To maintain safety, traffic volume at some facilities could be reduced, which might result in delays during busy periods."

Chicago’s O’Hare saw the most cancellations Sunday, as some 517 flights heading into and leaving the Windy City combined were grounded.

At least 287 flights either leaving or heading to Denver were canceled. New Jersey’s Newark Liberty International Airport witnessed 125 cancellations.

Atlanta’s Hartsfield-Jackson International Airport saw 60 outbound flights canceled – with another 56 flights meant to arrive at the airport Sunday canceled.

Nearly 2,000 more flights were delayed across the country, according to the online tracker.


"With high passenger volume, potential weather issues, and possible staffing impacts we expect increased security wait times today and Mon," the Atlanta airport wrote in a Twitter alert posted early Sunday. "Please arrive at least 2.5 hours prior to your scheduled departure time, and 3 hours early if you require special assistance."

Videos posted to social media showed extensive lines outside the terminal at several airports. Those included at Fort Lauderdale-Hollywood International Airport in Broward County, Florida, where one user lamented that the line for Spirit Airlines extended from terminal three until terminal 4.

"It’s a complete cluster. Understaffed. Underprepared," the user wrote. "My son is flying Unaccompanied back to his dad - the only flight to his destination - no one will assist. Do not recommend."