Thousands of flights were delayed and canceled during the record travel weekend of July 4th

Travelers are returning to airports in record pre-pandemic numbers this July 4 bank holiday weekend but continue to face thousands of delayed and canceled flights, data shows.

The Transportation Security Administration screened 2,490,490 passengers at airport security checkpoints on Friday — the highest number of passengers since Feb. 11, 2020, when the agency screened more than 2.5 million passengers. Agency spokeswoman Lisa Farbstein tweeted on Saturday.

On the same day, 464 U.S. domestic and international flights were canceled and more than 6,600 delayed, according to flight tracker FlightAware, which found this accounted for 28.8% of total scheduled flights.

More than 930 flights within, to or from the United States were delayed and more than 200 flights were canceled as of Sunday morning, FlightAware said. New York’s John F. Kennedy International Airport, Hartsfield-Jackson Atlanta International Airport, and Chicago O’Hare International Airport had the highest rates of delays and cancellations.

According to FlightAware, 53 flights within, to or from the United States for July 4 were already canceled as of Sunday morning.

Sunday’s cancellations followed Saturday’s 5,893 delayed flights and 655 canceled flights within, to or from the United States.

The July 4 weekend flight cancellations and delays also follow those of June 16 and Father’s Day weekend, which included the busiest air travel day of the year leading up to July 1 and saw more than 3,300 flight cancellations Friday through Monday and Memorial Day weekend around 2,700 flights were canceled.

The surge in cancellations follows staffing shortages, and particularly a pilot shortage, which has prompted some airlines to preemptively cancel thousands of flights for the summer season.

Airline executives have blamed the Federal Aviation Administration’s understaffing for flight cancellations and delays, but in an official statement, the FAA has denied that allegation.

In an interview with the AP last month, Transport Secretary Pete Buttigieg said he wanted to see how air travel fared over the Fourth of July weekend and the rest of the summer before determining whether his department would take enforcement action against airlines.

Buttigieg on Saturday tweeted about how passengers could request refunds for canceled flights, noting in a thread that his own connecting flight Friday night was canceled and that he was requesting a $112 refund.

“Airlines offer miles as compensation for some travel problems, and that’s often a matter of negotiation. It’s between you and the airline,” Buttiegieg tweeted. “But you are entitled to cash refunds for canceled flights – that’s a requirement we will continue to enforce.”

FlightAware spokeswoman Kathleen Bangs previously told NBC News that she expects the wave of cancellations to stabilize by the fall as airlines scale back schedules and aim to hire more pilots and other airline employees.