In this Friday, March 19, 2021 file photo, an airliner lands at Tampa International Airport in Tampa, Fla. On Sunday, March 21, more than 1.5 million people streamed through U.S. airport security checkpoints, the largest number since the pandemic tightened its grip on the United States more than a year ago. However, passenger traffic remains far below 2019 levels. (Photo by Gene J. Puskar/AP Photo)
