Jim Mack had made several trips to New York City before, but had never been the only passenger on a commercial jet landing at a deserted La Guardia Airport.
Instead of shuffling into the madhouse that is Terminal B on a typical weeknight, Mr. Mack was greeted by an eerie silence. “It felt like it was either closed or I had landed in the wrong terminal,” he said.
He had flown from Tampa, Fla. — just him and a Southwest Airlines crew — and now he was striding up the concourse toward baggage claim. The only luggage on the carousel was his. The lone Uber driver was waiting for him.
The coronavirus pandemic has unraveled air travel in the United States and turned some of the world’s busiest airports into giant voids.
The nation’s air-traffic system is still functioning. But airlines have slashed their schedules, and even on the dwindling number of remaining flights very few seats are filled.
The Transportation Security Administration screened just 87,534 travelers across the country on Tuesday, the smallest number ever. That was down from 2.21 million on the same day a year before, an extraordinary drop of more than 95 percent.
Mr. Mack, a frequent flier who was in New York to coordinate the placement of additional nurses at overburdened hospitals, said Tampa International Airport had also been shockingly quiet.
Across the country, at many major airports from Boston to Los Angeles to Chicago, the scene is much the same: vast terminals devoid of the usual line, shops shuttered and scant sightings of passengers.
Leisure travel and virtually all business trips have ceased. The usual cacophony of flight announcements has been largely silenced.
At John Wayne Airport in Santa Ana, Calif., the sound of a jet pilot playing a piano echoed through a desolate concourse.
In the New York metropolitan area, all three major airports — La Guardia, Kennedy International and Newark Liberty International — are open, but just barely.
They are handling only about 5 percent of normal passenger traffic, said Rick Cotton, the executive director of the Port Authority of New York and New Jersey, which operates the airports.
At La Guardia, Delta Air Lines, its dominant carrier, has cut back to just 15 flights a day, down from about 150 before the pandemic. United Airlines did likewise at Newark Liberty, one of its hubs, keeping just 15 of about 140 daily flights.
JetBlue Airways said last week that it would suspend operations at eight airports, including La Guardia, on the East and West Coasts.
Most of the thousands of people employed at the New York airports have been laid off, many without severance or health insurance.
Mr. Cotton said the Port Authority had pressed the companies that employ the bulk of them — airlines, contractors and concessionaires — to consider them furloughed and to plan to bring them back when they are needed.
The agency has allowed operators of stores and restaurants in the airports to temporarily forgo paying part of their rents, he said.
Mr. Cotton, who tested positive for the coronavirus last month and is out of quarantine, also said he found it “really stunning” to see three of the country’s busiest airports so empty and quiet.
“I don’t think anyone has seen anything like this,” Mr. Cotton said on Tuesday after touring Terminal 4 at Kennedy. “These facilities were built for more than 20 times the number of passengers we’re getting.”
But he said the agency intended to operate them indefinitely as a public service so that essential workers could travel.
The Port Authority worked with airlines to pare back their presence so that some sections, including Terminals 2 and 7 at Kennedy, could be closed off, Mr. Cotton said.
At La Guardia, Delta has shifted operations from Terminal D, which will be replaced by a new terminal that is under construction, to the adjacent terminals. At Newark Liberty, United has consolidated almost all of its operations in Terminal C.
Nearly all of the hundreds of stores at the three airports are closed, but a few restaurants are selling food on a “grab and go” basis, Mr. Cotton said.
Customers can eat the food on planes or at their gates. “Social distancing is not a problem” at the airports these days, Mr. Cotton said.
One of the shops that has held on in Terminal 4 at Kennedy is Chocolate & More, a sweets shop that has added hand sanitizer and disinfecting wipes to its usual wares.
It is the only one of 17 shops operated by Paradies Lagardère, a Paris-based company, in the terminal that did not close, said Mark Fletcher, who manages the stores.
“It’s definitely a different experience,” Mr. Fletcher said. “Terminal 4 is the busiest terminal at J.F.K. It’s typically a zoo over there.
“Now there are just big gaps between the flights when you won’t see anybody,” he said. “We saw one today that maybe 30 people got off and that seemed like a lot.”
Mr. Fletcher said his company has four shops open in the neighboring Terminal 5, including a CNBC News store that sells books and magazines.
Business is “not near what we did” before the pandemic led to broad restrictions on travel, but, he said, “We’re doing enough to stay open.”
The company had to lay off all but about 20 of about 200 employees, most of whom were members of the Unite Here union. He said that many of them were collecting unemployment benefits and waiting for word on when some of the shops might reopen.
Jessica Micucci had just bought some food from the only place she could find open near her gate at John Wayne Airport — a McDonald’s — when she heard classical music filling the concourse. She spotted a man in a pilot’s uniform playing a small grand piano.
Ms. Micucci, 42, said he told her that he never played in public, but his shyness faded in the seclusion. With his permission, she shot a short video on her phone.
She was so moved by the moment that tears ran down her protective mask, she said.
Ms. Micucci, who was going to Florida with her two young children, was initially reluctant to post the video on Facebook for fear of being shamed for traveling during the pandemic. But she said the response there had been overwhelmingly positive.
On her trip to her mother’s house near Orlando, she changed planes at Dallas/Fort Worth International Airport. She said she saw more fellow travelers there, but almost none with children.
Orlando International Airport was the only one she passed through that was even slightly busy, she said.
Mr. Mack, 57, had no qualms about his reason for traveling halfway across the country from his home in Overland Park, Kan. His employer there, Krucial Staffing, recruited nurses from around the country to help out in New York City hospitals inundated with Covid-19 patients.
A notice on the company’s website sought 400 registered nurses, offering them $10,000 a week for three weeks. When they arrived at a hotel in Midtown Manhattan, Mr. Mack would be there to greet them and help them get situated.
After landing at La Guardia on Thursday, Mr. Mack said he was not fearful about getting sick himself. But he was puzzling over a conundrum he had not faced on his previous trips to New York: how would he occupy his spare time.