Rush hour is now anything but at the Montgomery Street station in the heart of San Francisco.

Gone are the laptop-toting workers jostling into trains beneath the high-rise offices of lucrative tech companies. At 5:30 p.m. on a recent weekday, a woman hauling oversized shopping bags with three young girls easily secured several rows of seating.

Three years after the pandemic began, remote work endures as a way of life for many office workers, and few major transit systems in the United States have suffered worse than Bay Area Rapid Transit. The 131-mile network depends heavily on suburban residents who commute daily into San Francisco and less than other transit systems on local passengers trying to get across town.

Weekday ridership on BART is down to 32 percent of what it was before the pandemic began, punctuating a desperate moment for San Francisco. Without daily foot traffic, major retailers are abandoning downtown, and analysts believe the city core has yet to bottom out. Homeless encampments and open drug use have further discouraged visitors, while passengers have complained about safety and a lack of cleanliness.

BART officials are starting to come to terms with a future that no longer revolves around a downtown work culture. They are considering whether to pivot toward serving more concertgoers and sports fans on nights and weekends.

Across the United States, transit systems that have relied for decades on office workers are scrambling to avoid financial collapse as commuters stay home. Many systems are asking their local governments for bailouts as federal pandemic relief runs dry, but they are also racing to reinvent themselves.

Kansas City, Albuquerque and Boston have experimented with eliminating fares. Dallas is offering subsidized Uber rides to transit users. The Washington Metro is investing in housing and retail shops at dozens of its stations.

“If anyone says that they know the way out of this difficult situation, they’re fooling themselves,” said Brian D. Taylor, the director of the Institute of Transportation Studies at the University of California, Los Angeles. “This is a really challenging time.”

In the San Francisco region, BART was created a half-century ago to alleviate congestion as more commuters headed into the city for work. Before the pandemic, the system was so popular that trains were often overcrowded. There was talk of spending $15 billion to build a second underwater tunnel to ferry even more train passengers into downtown San Francisco.

But the riders that had packed BART trains have also proved to be a liability in a post-Covid world in which tech workers and other professionals have stayed home.

BART has one of the nation’s lowest public transit rates compared with before the pandemic, according to data from the American Public Transportation Association. Other California agencies are faring better than BART’s 32 percent — the San Francisco-focused Muni line is at 58 percent, Los Angeles’s bus and train system is also at 58 percent and the AC Transit bus system, based in Oakland, is operating at 54 percent capacity. The New York City subway and bus network is at 72 percent.

Alejandra Alvarez, 65, has for two decades commuted on BART from the East Bay suburb of Richmond to San Francisco to work the front desk at a doctor’s office, and has watched the numbers of rush hour passengers decline over the past few years. Once, she said, a man tried to rip her iPhone from her hands. Another time, a woman undressed in the train car.

“There are days like that, and there are days when it’s smooth sailing,” said Ms. Alvarez, as she waited behind the yellow platform line to catch her BART train home on a recent evening. “And it’s less crowded now, which is kind of nice.”

BART and other transit operators are losing revenue for each empty seat or row at rush hour. Bus and rail systems have been relying on billions of dollars in federal Covid relief funds to keep operating, but the money is expected to run out within a few years, transit leaders say.

In California, after transit agencies pleaded for help, the State Legislature agreed last week to provide $1.1 billion over three years to avoid harsh cuts in public transportation. State lawmakers also decided to redirect $2 billion from transit infrastructure to daily operations — a sign that once-bullish expansion dreams are giving way to survival needs. Gov. Gavin Newsom, who had initially proposed slashing transit funds to reduce a $32 billion state budget deficit, still has to approve the budget proposals.

In the Bay Area, saving BART is also a matter of saving San Francisco. City leaders fear that transit cuts will further discourage office workers and tourists, making recovery even more difficult and creating a “doom loop.”

BART stands to gain a sizable share of the state funding passed by the Legislature. Robert Powers, the general manager of BART, said that he also hoped that changes such as shifting the train schedule to serve more leisure riders would buy the system time until it could find new funding or commuters return.

“We do think that the downtown economies in the Bay Area are going to bounce back,” Mr. Powers said. “We firmly believe that, and we’re going to be ready. We’re going to be there for the riders.”

Other transit agencies are experimenting with incentives and services. Next month, the Metro in Los Angeles will let passengers ride for free after they pay a certain amount each day or week.

Denver is offering free trips on its bus and rail system throughout July and August. The SEPTA system in Philadelphia is selling steeply discounted monthly transit passes to employers, including Wawa convenience stores and Penn Medicine, to discourage workers from driving.

In Seattle, children have been able to ride public transit for free since last fall, an effort to cultivate the next generation of public transportation users, said Dow Constantine, the county executive of King County. The county also provides a free transit pass to anyone who sees a hockey or a basketball game at the Climate Pledge Arena in downtown Seattle.

Mr. Constantine said he wanted the efforts to rebuild ridership “in what I think is a permanently changed environment.”

Large-scale changes that would increase transit use — more development near stations, congestion pricing or limiting parking in cities — generally are not in the purview of transit agencies, said Ethan Elkind, an environmental law professor at the University of California, Berkeley, who wrote a book on the history of the Los Angeles subway system.

“You can put the New York City subway in the middle of Oklahoma and you wouldn’t have any ridership — that’s kind of the harsh reality for American transit,” Mr. Elkind said. “There’s only so much they can do with service and fares to lure riders back.”

In many cities, riders may need to go to the office only on Wednesdays. Or they want to pick up their children from school in the middle of the day or make a run to the grocery store.

The Dallas Area Rapid Transit, which operates buses and rail in the Dallas-Fort Worth metroplex, unveiled a new bus network last year that scrapped some lesser-used routes, including a few that had been in place since World War II. DART also has increased the frequency of its more popular routes to make bus transportation more convenient for impromptu trips.

The Dallas agency has worked with Uber to provide discounted rides to customers that allow them to reach destinations that buses and trains do not. For $6, riders can purchase a day pass that covers the cost of rail, bus and Uber rides, said Gordon Shattles, an agency spokesman.

“The only thing we couldn’t move was the rail tracks,” Mr. Shattles said.