Sean Rossman

USA TODAY

Thousands of people packed train stations Saturday as they burrowed into the nation's capital for the Women's March on Washington.

Marchers tweeted photos of crowded platforms and overflowing train cars loaded with women and men wearing pink and carrying signs, many of which disparage newly sworn-in President Donald Trump.

The city's public transit service, the Washington Metropolitan Area Transit Authority, recorded about 275,000 trips as of 11 a.m. Saturday, more than the 193,000 it recorded by 11 a.m. Friday ahead of Trump's inauguration speech and parade.

Kevin Donahue, D.C.'s deputy mayor for public safety and justice, said march organizers estimate 500,000 are in attendance.

The huge crowd comes a day after empty space was spotted on the National Mall ahead of Trump's inauguration speech and bare bleachers were noticeable along the inaugural parade route. Officials estimated about 900,000 people would file into D.C. for Friday's parade and speech. That's about half the attendance at former President Obama's 2009 swearing-in, the largest event in the history of the nation's capital.

At a train station blocks from the White House on Saturday, trains filled with participants would stop, but there was no room for passengers. Finally, after three trains went by, a USA TODAY reporter was able to squeeze on.

On the train, participants sang I Will Survive. The message was likely march-related, but with the packed bodies and sweat, it also could double as making it off the train alive. Hundreds of people streamed out of the train when it stopped near the U.S. Capitol.

WMATA said parking at metro stations is full. March organizers said the street around the main stage is also at capacity and urged those still streaming in to find another way to the festivities.