No other city in America is as reliant on mass transit as New York, with millions of daily riders usually cramming into subway cars, trains and buses run by sprawling public agencies. But, before the coronavirus pandemic, more than 100,000 commuters also depended on a string of private bus companies to get them to their jobs in the city. Now, however, with fear of infection keeping most workers away from their offices even as New York slowly reopens, that herd of buses has thinned and the companies that operate them are struggling to survive.

Already, one of the oldest commuter-bus companies in the New York region has suspended all of its operations. Others, with ridership down 90 percent or more from pre-pandemic levels, have drastically reduced service and are pleading for financial help from the federal government.

“Through World War I, World War II, 9/11, the housing crisis, Hurricane Sandy, people were still going to work,” Mr. DeCamp said from his company’s headquarters in suburban Montclair, N.J. “Right now, you’re just seeing nobody going to work.” DeCamp’s daily ridership had fallen from more than 6,500 passengers to less than 400, Mr. DeCamp said. With no pickup in sight, he felt he had no choice but to park his fleet of about 50 buses and furlough his work force, which included about 110 unionized drivers and mechanics.

Laying off the workers, some of whom had worked for DeCamp for more than 30 years, was “soul-crushing,” he said. Transportation companies often have to adjust schedules to account for fluctuations in demand, but they are loath to suspend service altogether because loyal customers may have no alternative. That is one reason so many private operators are still running buses despite the slim ridership.