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.