The crowd for the march was estimated at 600,000 for Los Angeles, 300,000 in Chicago and 200,000 in New York City, though there were many other protests in smaller cities. Over the weekend, European cities saw activists gathering too, including London and Rome.
USA organizers issued a unifying declaration of principles for the 2018 Women's March: "We believe that Women's Rights are Human Rights and Human Rights are Women's Rights".
Several hundred protesters also gathered in Palm Beach, Florida near Mr Trump's Mar-a-Lago home.
"No one and nothing will be great unless it costs you something", Davis said in Los Angeles.
People in Florida dressed up like characters from the TV show "The Handmaid's Tale".
Oscar victor Natalie Portman has told how an environment of "sexual terrorism" as a teenager led to her covering up her body and "inhibiting her expression and her work", as Scarlett Johansson called out fellow actor James Franco over allegations of sexual misconduct. A vocal supporter of equality, Davis gave a hair-raising speech in the wake of the #MeToo movement, after Harvey Weinstein sexual harassment scandal broke out previous year, the media reported.
The protests were held on the first anniversary of Trump's inauguration as president of the US and several of the marchers held signs criticizing the former reality TV star.
The signs at the protest focused on a range of social and political issues.
These were the voices that were seen and also heard.
Supported by Longoria and Constance Wu, who were standing, arm in arm, behind her, Portman took to the stage and spoke about starring in her first film, The Professional, at the age of 12. Among the goals of this year's march are getting more Democrats to run for public office and bolstering voter registration.
Portman was among dozens of celebrities who joined women in cities across the U.S. donning the famous pink knit "pussy hats" - a reference to Trump's videotaped boasts of his license to grope women without repercussions. "Lowest female unemployment in 18 years!", he tweeted.
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