Organisers say more than 3,100 events have been registered in all 50 states, with more than nine million people expected to participate.
In Washington, hundreds of marchers moved through the streets, past the Lincoln Memorial and into the National Mall, holding signs that read “Put down the crown, clown” and “Regime change begins at home”.
Demonstrators rang bells, played drums and chanted “No kings”.
Demonstrators rally near the Lincoln Memorial (Allison Robbert/AP)
The Trump administration’s aggressive immigration enforcement actions, particularly in Minnesota, were just one item on a long list of protesters’ grievances that also included the war in Iran and the Trump administration’s rollback of transgender rights.
In New York City, Donna Lieberman, executive director of the New York Civil Liberties Union, described Mr Trump as the nation’s “Bully in Chief” and said Minneapolis residents “forced the wannabe king to withdraw his shock troops”.
“They want us all to be afraid to protest,” she said during a news conference.
“They want us to be afraid that there’s nothing we can do to stop them. But you know what? They are wrong — dead wrong.”
The White House dismissed the rallies. Spokesperson Abigail Jackson described the protests as the product of “leftist funding networks” with little real public support.
Demonstrators rally in front of the Lincoln Memorial (Jose Luis Magana/AP)
Ms Jackson said in a statement that the “only people who care about these Trump Derangement Therapy Sessions are the reporters who are paid to cover them”.
The National Republican Congressional Committee was also sharply critical.
“These Hate America Rallies are where the far-left’s most violent, deranged fantasies get a microphone,” said Maureen O’Toole, spokesperson for the NRCC.
Organisers have designated the rally at the Minnesota Capitol in St Paul as the national flagship event, in recognition of how the state where federal agents fatally shot two people who were monitoring Mr Trump’s immigration crackdown became an epicentre of resistance.
Headlining that observance will be Bruce Springsteen, performing Streets Of Minneapolis, which he wrote in response to the deaths of Renee Good and Alex Pretti, and in tribute to the thousands of Minnesotans who took to the streets over the winter.
Springsteen’s Land of Hope & Dreams American Tour, which has a “No Kings” theme, kicks off on Tuesday in Minneapolis.
Minnesota organisers have told state officials they expect 100,000 people could converge on the Capitol grounds, where last June’s event drew an estimated 80,000 people.
The St Paul rally will also feature singer Joan Baez, actor Jane Fonda, Sen Bernie Sanders and a long list of other activists, labour leaders and elected officials.
Rallies are also planned in more than a dozen other countries, from Europe to Latin America to Australia, Ezra Levin, a co-executive director of Indivisible, a group spearheading the events, said in an interview.
Countries with constitutional monarchies call the protests “No Tyrants”, he said.
For those unable to attend in person, another activist group, Stand Up For Science, is hosting a “virtual and accessible” event online.