More than 400,000 people marched through Manhattan on Saturday in solidarity with the Women's March on Washington, according to the Mayor's Office.
Organizers of the Women's March on NYC put the tally closer to 600,000.
Regardless of the exact number, hundreds of thousands of people, male and female, young and old, filled midtown Manhattan, marching from the United Nations headquarters along 42nd Street and up Fifth Avenue to Trump Tower, the president's residence and business headquarters before he moved to the White House.
"I'm heartened by the turnout and all the sister marches across the world," Megan Schulz, a 42-year-old director of communications from Brooklyn, said. "I think it's a beautiful thing."
No official estimates of the crowd size of the Washington march were available, but the demonstrators appeared to easily exceed the 200,000 organizers had expected.
In Los Angeles the Sister March estimated it drew 750,000 demonstrators, and a planned march in Chicago grew so large that organizers did not attempt to parade through the streets but instead staged a rally. Police said more than 125,000 people attended.
Protesters rallied in and around Dag Hammarskjold Plaza before Women's March on NYC, with Manhattan Borough President Gale Brewer telling the crowd, "We don't like that guy in the White House ... we are not kidding."
Actress Rosie Perez, who also spoke during an anti-Trump rally led by Mayor Bill de Blasio on Thursday, told the crowd that she was there to "let the administration know we are here ... and we will be respected."
"This is the most beautiful thing I've seen in a very long time. I am so filled with love and hope," she said.
"We've come out to say women matter. We matter," Katherine Siemionko, a lead organizer of the march, told the crowd.
Signs throughout the crowd bore messages including "we the people are greater than fear." One popular sentiment -- "women's rights are human rights" -- was echoed by "Orange is the New Black" star Taylor Schilling, who told the pre-march crowd: "I'm here because I believe in the power of action and love to conquer hate. ... We can tell this administration that we are going to be heard, and we are going to be seen."
Astoria resident Johanna Valentine, 29, proudly sported her "nasty women" shirt. Valentine, a family nurse practitioner who came to the march with her mom, said the repeal of the Affordable Care Act and women's reproductive rights were especially important to her.
"It's very inspiring," she said, looking around at the crowd. "It’s great to see so many generations here today."
Sheri Steinmetz, 56, took the train from Woodbridge, Connecticut, for the march. Her kids, she said, were marching in Washington.
"It's empowerment. We're excited to be here," said Steinmetz, a lawyer, adding she felt it was important to march for the simple fact that "we're Americans and Trump is our president. That's the best thing I can say without swear words."
Other politicians and celebrities who spoke included the city's first lady, Chirlane McCray, Rep. Carolyn Maloney (D-Manhattan), and city Comptroller Scott Stringer, as well as actresses Cynthia Nixon, Whoopi Goldberg and Helen Mirren.
Maloney said that when women succeed, America succeeds.
“And when I see President Trump, I'm going to ask him: 'Where are the women?'" she told demonstrators. "You are the leaders of today and tomorrow."
Calling the march "a historical moment," Stringer rallied the protesters to take action.
"I'm so honored to be here as a man, standing side by side with the women of the world," he said. "We are going to organize, we will agitate, we're going to fight back. We're just getting started."
Nixon said Washington should think twice before messing with women, and they “better think twice before messing with New Yorkers.”
"We are not rolling back the clock on the progress we have made," she said, adding she was raised by a single mother. "Remember that throughout history when women organize, change happens."
Marchers had planned to take their rally cries -- messages on signs included "I'm here for my future" and "love trumps hate" -- to the doors of Trump Tower, but police stopped them south of the building on East 55th Street.
Despite the massive size of the march, demonstrators remained largely peaceful. Police said there were no arrests as of Saturday evening.