That is raising concerns about the potential long-term damage to an essential transport method for millions of lower-income Americans even as air travel has shown signs of picking up since the Thanksgiving holiday period.

And those who have to take the bus, for whatever reason, are finding fewer options, and often higher prices as a result.

Feeling the pinch most are people like Andrew Sarkis. He paid $97 for a one-way bus ticket from Hampton, Va., to New York City, a 12-hour journey that required two transfers.

"It's expensive, man," said Sarkis, while stretching his legs after his bus took a brief stop at Union Station in Washington, D.C. "I used to go on another bus for $45 a trip, that goes straight to New York," he added.