Women’s March on Washington: What You Need to Know

From the beginning, the purpose of this march has been to challenge Mr. Trump’s administration.

“We’re doing it his very first day in office because we are making a statement,” one organizer, Breanne Butler, said in an interview days after the election. Of the the marginalized groups she accused Mr. Trump of attacking during his campaign, she said, “We are here and we are watching. And, like, ‘Welcome to the White House.’”

As the women’s group has become more organized, four co-chairwomen have refined the mission to specifically elevate groups like immigrants and minorities. Groups focused on immigration rights, including Define American and United We Dream, are partners with the group. Abortion rights will also be on the agenda: Naral Pro-Choice America and Planned Parenthood are both encouraging people to attend.

More than 30 other groups have joined as partners, including the Muslim Women’s Alliance, the Trayvon Martin Foundation, Girls Who Code and Black Girls Rock.

Cassady Fendlay, a spokeswoman for the organizers of the march, said that as many as 200,000 people could participate. She said organizers did not have a firm figure, but that they were monitoring replies to their invitations on Facebook and Eventbrite.

Law enforcement authorities in Washington are planning for a crowd that could swell to 400,000, according to Christopher T. Geldart, the director of homeland security for the District of Columbia. He said his office was monitoring reservations on Amtrak, for charter buses and for motel and hotel rooms, as well as comparing the event to previous marches to better estimate the size of the coming crowd.

He said his office was also planning for the possibility that other demonstrations could occur that day.

“We’re basically not going to stand anything down after the inauguration,” Mr. Geldart said, referring to the additional police and National Guard units that will be in the capital to assist local law enforcement authorities. “We’re leaving that stuff in place.”

The march will start at 10 a.m. at Independence Avenue and Third Street S.W., near the National Museum of the American Indian. Participants will hold several events for an hour or two before the march begins, Ms. Fendlay said. The final route has not yet been determined.

The event could last until 5 p.m.

The march does not yet have a confirmed host or M.C., and it is still unclear what sort of program will be offered. Gloria Steinem and Harry Belafonte are honorary co-chairs, but Mr. Belafonte, 89, had not decided if he will attend, his assistant, Ingrid Ellis, said Monday.

On their social media accounts, the actresses Julianne Moore and Jessica Chastain and the comedian Amy Schumer are among celebrities who have said they would attend.

Of course.

Any way they can. Buses seem to be a popular mode of transportation. Rallybus is one site marchers are using to find transportation.

Marchers will also be arriving from outside the United States. Julie Buchanan, an organizer in Toronto, said in an email that she was among 53 people chartering a bus for the trip to Washington.

Karin Blake Grana wrote in an email that she and a friend were flying in from Oslo to march. “We booked our plane tickets less than a week after the election,” Ms. Grana wrote. “We are that gung-ho.”

For those who cannot make it to Washington, sister marches are being organized all over the world, from Los Angeles to Oklahoma City to Athens. For those who still want to try to make it to the march in Washington, a site called MarchMatch.org is trying to help match travelers with carpools. One caveat: The website is not affiliated with the march and hasn’t been vetted for safety, Ms. Fendlay said.

Like travel, lodging will be up to the attendees. On the day of Mr. Trump’s inauguration, prices for hotel rooms are steep, but prices for Jan. 21, a Saturday, are somewhere in the neighborhood of reasonable, hovering around $300. Prices on Airbnb are not much cheaper. Outside of Washington, people are offering their homes and condos. One six-bedroom home near Bethesda, Md., a nearby suburb, is renting for $10,000.

Many within driving distance may try to make the trip to Washington and back in one day. That includes several busloads of New Yorkers, Ms. Fendlay said.

It is expensive. The marchers want to raise $2 million. So far, they’ve raised around $849,000, but that number is rising quickly. That money will pay for bus parking, hiring outside security to keep marchers safe and what might be the biggest necessity of any long march, port-a-potties.

That is still being decided. Possible options include lots at Robert F. Kennedy Memorial Stadium, but nothing has been confirmed. Organizers are asking that people traveling to the march register beforehand.

At least 20 groups have applied to march in Washington around the time of the inauguration, which is a record, according to Michael Litterst, a spokesman for the National Park Service. Among them are groups that support Mr. Trump.

Bikers for Trump, a group that gained attention for rallying at the Republican National Convention and promising extra security for Mr. Trump, is expecting 5,000 people to gather to celebrate at the John Marshall Park across from the National Gallery of Art on Constitution Avenue in Washington. According to its initial application with the Park Service, the group will be in Washington on Jan. 20 and 21. The group’s agenda is still unclear; Chris Cox, an organizer, did not respond to a request for comment on Monday.

The Progressive Independent Party has also filed an application with the Park Service to host a First Amendment demonstration in Anacostia Park, across the Anacostia River from Nationals Park in Southeast Washington.

Ms. Fendlay said that organizations that have joined in the march, which include Naral Pro-Choice America, Define American and Amnesty International, will be on hand to provide information to marchers about ways they can press their causes at home.

“There are a lot of people who have become part of this who are new to activism,” Ms. Fendlay said. “What we really hope is that they’ll check out our partners and what they’re doing in their hometowns and states.”