Long lines at the Bethesda Metro station slowed to a crawl as marchers tried to get to inbound trains Saturday. (Nick Anderson/The Washington Post)

Ridership on Metro for the Women’s March on Washington far exceeded official forecasts, with more than 597,000 trips taken by 4 p.m. Saturday — an unprecedented weekend ridership that was significantly higher than the number who traveled to attend the presidential inauguration Friday.

The crowds that filled downtown Washington were sizable enough to cause significant traffic backups around the region, as well as overcrowded parking lots, crush loads on Metro trains and hours-long waits for people seeking to buy fare cards at stations.

It was a dramatic departure from the transit situation Friday, when Metro ran rush-hour service all day, only to be met with moderate crowds that never reached the level of a normal weekday peak period. By 4 p.m. Friday, 368,000 trips had been taken on Metro. A total of 570,557 trips were logged by the close of the system.

On Saturday, thousands also arrived by charter bus at RFK Stadium. About half headed for the long lines waiting to ride Metro at Stadium-Armory station, while others chose to trek to the rally by foot on East Capitol Street.

In Baltimore, the lines at MARC commuter train stations were so long that the Maryland Transit Administration added extra train sets.

Some inbound Red Line trains, such as this one near Van Ness station, were jammed at 7:30 a.m. with people holding signs and wearing pink hats. (Alejandra Matos/The Washington Post)

Despite long waits and crowded trains, those who traveled for the march remained cheerful. Participants, many wearing pink hats or carrying signs, chatted with one another. Some riding on Metro offered snacks to strangers as trains stopped between each station for several minutes to avoid bunching.

Still, some of the participants wondered why Metro wasn’t better prepared for an event that many believed would bring historic crowds to Washington. Even though Metro opened two hours early and added two dozens trains, the early-morning crush still strained the system as marchers flocked to stations at the end of each line.

“We were projecting large crowds, but no one knows exactly what ‘large’ means,” Metro spokesman Dan Stessel said.

Service largely ran smoothly, he said. Some of the delays were caused by the large number of riders who had to purchase SmarTrip cards upon arriving at the stations. At some points, Metro had to close station entrances, send trains past crowded platforms and shut down escalators to accommodate the throngs of people.

L’Enfant Plaza station closed for under an hour in the early afternoon because of crowds inside the stop. The area outside the station was so packed that people trying to exit Metro had nowhere to go once they reached the sidewalk.

As the march wound down in the afternoon, Metro asked event participants to linger in the city before heading out to allow time for the crowds to ease.

The backlogs began early. By 8 a.m., when friends Andrey Arias and Danna Perez arrived at Shady Grove station, there were already throngs of people — more than 300, they estimated — outside the fare gates waiting to buy tickets.

They said it wasn’t until 10:15 a.m. that they were able to enter the station; it was another hour and 15 minutes before their Red Line train reached Gallery Place.

The experience was similar at Greenbelt station, on the northeastern end of the Green Line, where Maryland State Police closed the exit on the Capital Beltway for approximately two hours Saturday morning because of the stop’s overcrowded parking lot.

By 10 a.m., Metro said, many of the parking garages and lots around stations at the ends of lines were full or near capacity.

Those closures affected one group of marchers who chartered a bus from New York City; 22-year-old Chloe Gbai said she could see the lines of people from her window as the bus passed Greenbelt station and continued on to College Park.

Gbai said many people on the bus had tried to order one-day Metro passes in advance, but the cards had not arrived in the mail on time. The station manager at College Park was so exasperated with the long lines, Gbai said, that she began to allow people to enter the gates if they showed an emailed receipt for a previously purchased day pass.

“It was crazy, but it takes a lot more than a sh---y commute to keep women down!” Gbai said.

Parking at the Greenbelt Metro station was also a problem for Nilay Sheth and Jamie John, who drove from Ellicott City, Md. When police turned them away, they drove about half a mile and parked in an office building parking lot. They worried they might get ticketed or towed, but they didn’t want to miss the march.

“We don’t know if our car will still be there when we get back,” John said Saturday afternoon, shrugging.

Even so, she said, the drama was somewhat of a thrill.

“It’s my first time doing something like this,” John said. “There’s excitement in the air. Even though we had to wait a long time, we got to talk to people and listen to people, and it didn’t feel like a drag coming here.”

Kathleen Shumaker and Charice Putnam, visiting from North Carolina, said they had to wait 20 minutes at Tenleytown station so that three completely full trains could pass by. Finally, a fourth train arrived, a Metro employee shouted for the crowds to squeeze, and the two women jumped on.

“It was so packed,” said Shumaker, 25.

The trip toward Gallery Place, where they disembarked, was slow, with a few long stops. But the mood was cheerful, they said, and marchers talked to one another about what brought them out to the District on Saturday.

“It was frustrating, but it was also awesome, because it was great to see that we were all here for this,” Putnam said.

Robert Thomson contributed to this report.