Protesters from across the country are loading up on trains, planes, buses and carpools for the Women's March on Washington on Saturday, the day after President Donald Trump's inauguration.

NPR reports that organizers are expecting about 200,000 people to march on the National Mall. CNBC reports that another 600 "sister marches" are planned around the world for Saturday, too. It's estimated some 1.2 million people from Toronto to London, and even Iraq, will march in solidarity with the protesters in Washington.

The massive march was planned just weeks after being tossed around as an informal idea on the internet. ABC News reports that shortly after the election, Hawaiian grandmother Teresa Shook asked her female Facebook friends if they wanted to march together on Washington on Trump's inauguration day.

From there, the Women's March quickly took on a life of its own.

What started out as a protest to President Trump's victory against Democratic nominee Hillary Clinton is now being called a rally cry to remind the country of the need to protect and expand women's rights.

According to CNBC, the Women's March website lists its mission statement as, "In the spirit of democracy and honoring the champions of human rights, dignity, and justice who have come before us, we join in diversity to show our presence in numbers too great to ignore."

While women are a major voting category, this group is diverse. Protesters marching on the District of Columbia will be advocating for everything from abortion rights to the wage gap and expanded paid family leave.

A Women's March organizer, Carmen Perez, told NPR the protest is also about highlighting the inequalities faced by women of color, "This march was initially put together by white women, and a lot of women of color felt they weren't part of the conversation ... We have to make sure that we look up, that we begin to really coordinate our efforts."

The Women's March on Washington will begin at 10 a.m. Saturday, January 21. The rally is expected to last four hours. NPR reports it will kick off near the National Museum of the American Indian with speeches by Angela Davis, Gloria Steinem and the mothers of Trayvon Martin and Eric Garner.

The D.C. Metro will also be opening two hours early on Saturday to accommodate the influx of people trying to get to downtown Washington.