The Women's March on Washington is expected to be the largest demonstration around the inauguration of President-elect Donald Trump.
Organizers now say they are planning for about 500,000 people to attend.
Thousands or marchers poured into poured into Metro stations around the DC area Saturday morning.
PHOTOS: Protest signs from Women's March
The grassroots idea of a Women's March on Washington has turned into a major event. Lots of information is on its website and a Facebook video.
The official map for the Women's March:
"Everyone is welcome to march, no matter your age, your gender identity, or how you chose to vote," said Tamika Mallory, National Co-Chair of the march.
The march begins at 10 a.m. Saturday near the U.S. Capitol at the intersections of Independence Avenue and 3rd Street.
The video says there will be speakers and a short rally with performances, though an organizer said on Monday that she could not name any performers at this point.
Nor could she explain the march route, though the video says "we will march about one and a half miles together."
It's believed they will march toward the White House.
National Co-Chair Bob Bland said in the video, "The Women's March on Washington -- a permit for the route that we have chosen. There will be D.C. Police present to protect our route and marshals trained in non-violence for crowd control."
DC police will have rolling street closures along Independence westbound, and then north on 14th Street to Constitution Avenue, then west to 17th Street next to the Ellipse.
"And it is our mission to make sure that this march is as successful as possible. There will be space for people with disabilities, the elderly and pregnant women. We'll also have ASL (American Sign Language) interpreters throughout the rally. We'll have portable toilets for all and medical tents throughout the march," said National Co-Chair Linda Sarsour.
If you're going, organizers ask you bring signs, but none on sticks. No backpacks or large bags are permitted.
The best way to get there... Metro.
"Take the Yellow or Green Lines to L'Efant Plaza, Orange and Blue Line to Federal Center SW, Red Line to Judiciary Square, or Amtrak or Commuter Rail to Union Station. Walk toward the National Mall. There will be signs everywhere," said co-chair Mallory.
Given that the election was so divisive, march organizers are even putting out a legal hotline number in case people get in trouble. They are advising people to march with a buddy, make sure their cell phones are charged and let someone else know where they are.
More information can be found at womensmarch.com
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