March organizers said women are "hurting and scared" as the new president takes office and want a greater voice for women in political life.
"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," their mission statement says.
Retired teacher Linda Lastella, 69, who came from Metuchen, New Jersey, said she had never marched before but felt the need to speak out when "many nations are experiencing this same kind of pullback and hateful, hateful attitudes."
"It just seemed like we needed to make a very firm stand of where we were," she said.
Rose Wurm, 64, a retired medical secretary from Bedford, Pennsylvania, boarded a Washington-bound bus in Hagerstown, Maryland, at 7 a.m. carrying two signs: one asking Trump to stop tweeting, and one asking him to fix, not trash, the Obamacare health law.
"There are parts of it that do need change. It's something new, something unique that's not going to be perfect right out of the gate," she said.
Many arrived wearing hand-knit "pussyhats" — a message of female empowerment aimed squarely at Trump's crude boast about grabbing women's genitals.
The march attracted significant support from celebrities. Ferrara led the artists' contingent, and those scheduled to speak in Washington included Scarlett Johansson, Ashley Judd, Melissa Harris-Perry and Michael Moore. The promised performance lineup included Janelle Monae, Maxwell, Samantha Ronson, the Indigo Girls and Mary Chapin Carpenter. Cher, Katy Perry and Julianne Moore all were expected to attend.
Women and other groups were demonstrating across the nation and as far abroad as Myanmar and Australia. In Prague, hundreds gathered in Wenceslas Square in freezing weather, waving portraits of Trump and Russia's Vladimir Putin and holding banners that read "This is just the beginning," ''Kindness" and "Love."
"We are worried about the way some politicians talk, especially during the American elections," said organizer Johanna Nejedlova.
In Copenhagen, march organizer Lesley-Ann Brown said: "Nationalist, racist and misogynistic trends are growing worldwide and threaten the most marginalized groups in our societies including women, people of color, immigrants, Muslims, the LGBT community and people with disabilities."
In Sydney, thousands of Australians marched in solidarity in Hyde Park. One organizer said hatred, bigotry and racism are not only America's problems.
The idea for the women's march took off after a number of women posted on social media in the hours after Trump's election about the need to mobilize. Hundreds of groups quickly joined the cause, pushing a wide range of causes, including abortion rights, gun control, climate change and immigrant rights.
While the march organizers' "mission and vision" statement never mentions Trump and stresses broad themes, including the message that "women's rights are human rights," the unifying factor among those turning out appeared to be a loathing for the new president and dismay that so much of the country voted for him.
Friday's unrest during the inauguration led police to use pepper spray and stun grenades to prevent the chaos from spilling into Trump's formal procession and the evening balls. About a mile from the National Mall, police gave chase to a group of about 100 protesters who smashed the windows of downtown businesses, including a Starbucks, a Bank of America and a McDonald's, as they denounced capitalism and Trump.
"They began to destroy property, throw objects at people, through windows. A large percentage of this small group was armed with crowbars and hammers," said the city's interim police chief, Peter Newsham.