A day after Donald Trump became the 45th President of the United States, hundreds of thousands took to the street to in a mass march designed to send message to the President and his administration.

Massive numbers of demonstrators flooded cities across the U.S. and the world in peaceful protests to voice their concerns.

"We march today for the moral core of this nation, against which our new president is waging a war," actress America Ferrera told the crowd. "Our dignity, our character, our rights have all been under attack and a platform of hate and division assumed power yesterday. But the president is not America. We are America and we are here to stay."

As the Washington march was expected to draw as many as 200,000 people, cities across the country and the world, from San Diego to Sydney, Australia, saw similar robust gatherings — a point made by the event's honorary co-chair and feminist icon Gloria Steinem.

For Trump, whose presidential campaign was dogged by past allegations against him of sexual harassment, Steinem had more pointed advice: "A Twitter finger must not become a trigger finger."

"I wouldn't call it an anti-Trump march, I would call it a 'We are watching you, Trump' kind of march," said Ayesha Ahmed, who came from Chicago with the Muslim Women's Alliance. The march also attracted significant support from celebrities, with actresses Scarlett Johansson and Ashley Judd and singers Alicia Keys and Madonna speaking to the crowd. Performers included Janelle Monaé, Maxwell and the Indigo Girls.

Romaine Mills-Teque, who is African-American, rode down from Boston with her daughter, Brianna. "I didn't think I'd have to do this for my daughter because my mother and grandmother marched fought for civil rights and women rights for me," she said. "But I will continue to do it until the right is wronged."

"It's the most powerful experience I think I've ever had in my life," she said, surrounded by thousands of like-minded women. Marchers have mobilized in U.S. cities, from Boston to Philadelphia to New York City.

"It's become a global movement, an outlet, inspiring people all over the world to fight for equality and social justice," said Tina Cassidy, one of the organizers of the sister marches. "Women everywhere are standing up."

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