The rallies were similar to the marches soon after Trump's inauguration as president a year ago.
And true to form, Mr Trump was quick to needle the protesters by urging more women to flood the streets and celebrate the "unprecedented economic success and wealth creation that has taken place over the last 12 months".
Joblessness among women was 3.7 per cent in December, below the overall US unemployment rate of 4.1 per cent, according to the Labor Department.
Last year, a sea of demonstrators brought downtown Washington to a standstill, in a parade of knitted, pink "pussy hats", an allusion to Trump's videotaped boasts of being able to grope women with impunity.
The caps quickly became a symbol of women's empowerment and opposition to the new president in the early days of his administration.
"We want to continue the fight to resist this President and the policies we're against", said Sara Piper, 59, a geologist from Reston, Virginia.More news: Aguero treble gets City back on track as United eye Sanchez
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"The idea [behind the organisers' action] is that it is not enough for people to show they are angry or frustrated with the Trump administration's policies".
Still others chanted "Equal work, equal pay". "The message this year is marching to action: march, register, vote".
Sixteen-year-old Caley Medina said she wanted to spread her activism beyond her high school campus, so she came to the march with her mom and brother. In the intervening year, a string of reports laying bare pervasive sexual harassment and misconduct in workplaces from Washington D.C.'s Capitol Hill to Hollywood's studios have added further texture to the movement, with anti-Trump fervor remaining at, or at least near, its core.
This wasn't the only challenge to white women posed at Saturday's rally.
In a statement before the London march, activists said they were "coming together to pledge that we are going to make change in big and small ways".
"I was watching the news and have been keeping up with [Trump's] slander", rallygoer Danielle Miller told Blavity. "Maybe they are trying to cast as wide a net as possible", Ms Dalmia said.
The strapline for Las Vegas is "Power to the Polls", created to drive national voter registration and maximize women's involvement in the 2018 midterm elections, in which a record number of women are standing for election.