A day after President Donald Trump's inauguration, hundreds of thousands of people will converge on the National Mall for the Women's March on Washington.
Here's everything you need to know if you're attending -- or want to avoid the area:
When and Where Is the Women's March?
The event Saturday, Jan. 21 began with a rally from 10 a.m. to 1:15 p.m. near the Capitol, at Independence Avenue and 3rd Street SW.
Participants then will march toward the White House.
What's the Purpose of the March?
March organizers said in a mission statement posted to their website that participants will unite to end violence and promote rights for women, LGBT people, workers, people of color, people with disabilities and immigrants.
"The Women's March on Washington will send a bold message to our new government on their first day in office, and to the world that women's rights are human rights. We stand together, recognizing that defending the most marginalized among us is defending all of us," the site says.
While's Trump name does not appear in the group's mission statement, opposition to the president-elect appears to be what unites participants.
Who Is Organizing the March?
After Trump won the presidency, a retired attorney in Hawaii posted to Facebook about marching in Washington, The Washington Post reported. By the time Teresa Shook went to sleep, 40 women said they wanted to march. By the time she woke up, that number had ballooned to 10,000, the Post reported.
The idea for the march took off, and Shook and the initial organizers handed the reins to a group of experienced activists: Bob Bland, a fashion industry entrepreneur; Tamika Mallory, an organizer and gun-control advocate; Carmen Perez, executive director of the Gathering for Justice, a criminal-justice-reform group; and Linda Sarsour, executive director of the Arab American Association of New York.
How Many People Are Expected to Attend?
The deputy mayor of D.C. said 500,000 people were expected in the National Mall area for the march.
Christopher Geldart, the director of D.C.'s homeland security agency, said he expects that even more people will attend, based on bus registrations and train bookings.
As of Jan. 13, D.C. had received about 1,800 requests for permits to park tour buses on Jan. 21, Councilmember Charles Allen told News4. Just about 200 permits had been requested for Inauguration Day itself.
As of 1 p.m. Jan. 17, more than 203,000 Facebook users indicated on the Facebook page for the march that they would attend.
How Can I Get There?
The Metrorail system opened early and ran additional trains on Saturday. The system opened at 5 a.m., instead of the usual 7 a.m. Riders can expect trains every 4 to 6 minutes on every line.
Anyone taking Metrorail to the march is advised to use the L'Enfant Plaza or Capitol South stations, to avoid crowding.
See Metro's website for full details on how to use the system. Anyone who needs a Metro card is advised to buy it in advance to avoid long lines.
Metrobus will run on its regular Saturday schedule. Buses will detour around road closures on Independence Avenue between 2nd and 14th streets NW.
The D.C. Streetcar system will run from 5 a.m. Saturday until 2 a.m. Sunday.
The D.C. Circulator won't be running its National Mall route. All other routes will operate on their normal weekend schedules. (Note: The Union Station-Navy Yard and Potomac Avenue-Skyland routes don't run on the weekends during winter.)
Capital Bikeshare, which had closed its stations within the security perimeter for Trump's inauguration, will reopen those stations on a rolling basis Saturday. Check Capital Bikeshare's website or the SpotCycle app beforehand to see which stations are available, D.C. officials said.
Capital Bikeshare will have a bike corral at 4th and E streets SW Saturday from 7 a.m. to 5 p.m. A bike valet will be available at 10th Street and Independence Avenue SW. Find more information online here.
People from many states are planning to get to the march by bus. March organizers have a bus finder webpage to help people find buses to take them to Washington.
Anyone who plans to drive to the march is advised to expect heavy traffic and extremely limited parking.
Will Any Roads Be Closed?
Several roads near the National Mall will be closed from 3 a.m. to 6 p.m. Saturday, including 3rd Street NW from Constitution Avenue NW to C Street SW, and Independence Avenue SW from 1st Street to 6th Street SW.
Is the March Free? Do I Need to Register?
The march is free. Organizers are asking people who expect to attend to fill out a brief online registration form to help the hosts plan the event.
Will the March Be Safe?
D.C. police and the National Park Service have been in communication with march organizers about the planning of the event.
Organizers say they have hired a private security firm and will have "numerous professional security workers" at the event.
What's the Weather Forecast?
Saturday is expected to be mild and partly sunny, with temperatures in the 40s and 50s.
Where Can I Stay?
Some hotel rooms and Airbnb rooms in the region are still available, just don't expect a bargain.
Some groups, such as MarchBNB, are organizing to help march attendees find lodging. The list of those resources can be found on the march's FAQ page.
A gym in the Cleveland Park neighborhood is opening its doors to host a sleepover.
Can I Participate If I Use a Wheelchair or Have Mobility Issues?
March organizers say there will be a limited seated section and that more information will be available soon.
The ADA-accessible route will be 4th Street SW from C Street to Independence Avenue.
"It is our mission to make sure that this march is as accessible as possible," Sarsour said in a Facebook video.
What Am I Allowed to Bring?
All bags will be subject to search, and size restrictions will be in place. Folding chairs will not be allowed, nor will anything that could be construed as a weapon, including signs with sharp wooden handles. See the march website for full details.
Are Men Allowed?
March organizers say the march "is for any person, regardless of gender or gender identity, who believes women’s rights are human rights."
Which Celebrities and Public Figures Will Be There?
A long list of stars are expected to attend the march, including America Ferrera, Katy Perry, Cher, Scarlett Johansson, Zendaya and Julianne Moore.
The organizers of the event announced its performance lineup Wednesday. The list of performers includes Janelle Monae, Maxwell, The Indigo Girls and Angelique Kidjo.