Saturday marked the end of a pandemic era in the air: no more social distancing on flights.

Delta was the final holdout, ending its practice of blocking middle seats on Saturday. That is more than a year after the airline first introduced the practice as the coronavirus cratered the number of air travelers.

Other major U.S. carriers have long since returned to full flights. American and United starting selling all their seats last summer. Southwest started doing the same in December, and Alaska Airlines and JetBlue followed in January.

Delta announced at the end of March that it would make all seats available for flights starting May 1. One key factor, chief executive Ed Bastian said, was that the airline believed nearly 65 percent of those who flew with Delta in 2019 expected to have at least one dose of a vaccine by the beginning of May.

“While Delta’s decision to block middle seats has given many customers a reason to choose Delta over the past year, the signature hospitality of our employees and the experiences they deliver to customers every day have also deepened their trust in our airline,” Bastian said in an announcement.

During an earnings call in mid-April, Bastian said the change would provide “a powerful tool for improving our financial performance.”

The change comes as air travel continues to rebound over last year’s numbers. The number of passengers screened by the Transportation Security Administration has topped 1 million every day since March 11. At the lowest point during the same stretch last year, TSA screened fewer than 88,000 passengers in one day.

As they have packed their planes full again, airlines have pointed to an industry-funded study released last fall highlighting the relative safety of flying if precautions like constant masking and sanitizing are in place. A study in mid-April from the Centers of Disease Control and Prevention found that social distancing on planes was beneficial, but industry experts said they did not expect airlines to change their policies.

“With vaccinations accelerating and travel interest rebounding sharply, it’s more likely that President Biden will dunk a basketball on live TV than airlines will reimpose middle-seat blocking,” Scott Keyes, founder of Scott’s Cheap Flights, said in an email at the time.

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