Organizers expected millions of people to turn out by day's end at more than 2,600 planned rallies in major cities, small towns and suburbs, challenging a Trump-led agenda that has reshaped the government and upended democratic norms with unprecedented speed since he took office in January.

By all accounts, the demonstrations were largely festive, often featuring inflatable characters and marchers dressed in costumes. The demographically mixed crowds included parents pushing youngsters in strollers alongside retirees and people with pets in tow.

Little, if any, lawlessness was reported.

“There is nothing more American than saying, 'We don’t have kings’ and exercising our right to peacefully protest,” said Leah Greenberg, co-founder of Indivisible, a progressive organization that led planning of Saturday's events.

Demonstrators filled Times Square in New York City, where police said they made "zero protest-related arrests" even as more than 100,000 people rallied peacefully across all five boroughs.

Events in Boston, Philadelphia, Atlanta, Denver, Chicago and Seattle also drew crowds that each appeared to encompass thousands, if not tens of thousands, of people.

The protests reflected growing unease among many Americans, mainly on the ideological left, with developments such as the criminal prosecution of Trump's perceived political enemies, his militarized immigration crackdown and the sending of National Guard troops into US cities, a move Trump has said was aimed at fighting crime and protecting immigration agents.

As his administration has tried to rapidly implement its policies, Trump has installed inexperienced loyalists throughout the ranks of his administration and sought to apply pressure on the news media, law firms and universities.

Saturday's rallies were boisterous but orderly, with police largely keeping a low profile.

Demonstrators filled a street in Washington, D.C., to march toward the US Capitol, chanting and carrying signs, flags and balloons, as a carnival-like atmosphere prevailed.

Aliston Elliot, wearing a Statue of Liberty headpiece and holding a "No Wannabe Dictators" sign, said: "We want to show our support for democracy and fighting for what is right. I'm against the overreach of power."

In downtown Houston, US Marine Corps veteran Daniel Aboyte Gamez, 30, joined a crowd that officials said numbered about 5,000 at city hall.

"I don't understand what's going on in this nation right now," said Gamez, who served in Iraq, Afghanistan and Syria.

Trump has said little about Saturday’s protests. But in an interview with Fox Business aired on Friday he said that “they’re referring to me as a king - I’m not a king.”

While the Democratic Party has coped with internal divisions since Trump won re-election last year, party establishment figures such as Senate Minority Leader Chuck Schumer and progressive firebrands like US Representative Alexandria Ocasio-Cortez both voiced support for the "No Kings" movement.

Saturday's protests were aimed at building on momentum gained from more than 2,000 "No Kings" protests that were staged on June 14, coinciding with Trump's 79th birthday and a rare military parade in Washington.

House of Representatives Speaker Mike Johnson, a Republican, on Friday echoed a common refrain among his party, labeling the "No Kings" protests "the hate America rally."

Other Republicans have accused protest organizers of stoking an atmosphere that they said might spur political violence, especially in the wake of the September assassination of right-wing activist and Trump ally Charlie Kirk.

Vice President JD Vance, speaking on Saturday to a gathering of Marines at Camp Pendleton in Southern California, made no mention of the protests. But he criticized Democrats over the government shutdown that began early this month in a partisan standoff over federal appropriations.

Dana Fisher, an American University professor in Washington and author of several books on political activism, predicted that Saturday could see one of the largest protest turnouts in modern US history.

She expected that over 3 million people would take part based on registrations and participation in the June events. Overall turnout for the June 14 rallies was estimated at 4 million to 6 million, according to a crowd-sourcing analysis published by prominent data journalist G. Elliott Morris.