Protesters burned an orange-haired Donald Trump head in effigy, lit bonfires and blocked traffic as anger over the billionaire's election to the presidency spilled onto the streets of major cities.
From New York to Los Angeles, thousands of people marched, rallied and chanted in around 10 cities against the billionaire president-elect a day after his stunning upset win, some carrying signs with slogans such as "Not our President" and "Love trumps hate."
Most of the rallies were peaceful.
Police said they had arrested 15 people, the New York Times reported.
In Washington, several hundred gathered in front of the White House for a candlelight vigil on a damp, chilly evening, criticizing what they called Trump's racism, sexism and xenophobia, and carrying signs reading "We have a voice!" and "Education for all!"
One of the organizers, Ben Wikler, Washington director of the liberal advocacy group MoveOn.org, told the crowd that others were coming together in hundreds of communities around the country.
"People are justly frightened," he said. "We are here because in these darkest moments, we are not alone," he added, before leading chants of "We are not alone!"
Protests were also held in Chicago, Philadelphia, Boston, Portland and other cities.
In Oakland, California, protesters lit fires in the street and stood around them chanting, news reports said. Some threw bottles and firecrackers at police, KPIX TV reported.
In Los Angeles, demonstrators outside City Hall held aloft a burning, box-shaped likeness of Trump's head, topped with bright orange hair.
Ethan Miller of the workers' rights group Jobs with Justice said organizers held the Washington vigil to show that civil society was resilient.
"It's a hard time for a lot of Americans," he told AFP. "We saw a campaign that was filled with racism and misogyny and whole host of other terrible tactics that ultimately were successful for winning the electoral college."
"But we're not going to let a Donald Trump presidency stop the progress in this country," he added.
Electoral system 'broken'
In New York City, demonstrators gathered in Union Square holding signs saying "Love Trumps Hate" and "Trump Grabbed America by the Pussy!" before marching uptown in the thousands to chant in front of Trump Tower.
"The electoral college is broken," protester Nicholas Forker said of the US indirect voting system. "I think it definitely needs to be reformed... I think it's ridiculous."
In Chicago, several thousand people gathered around Trump Tower, blocking downtown streets and traffic while other staged a counter-protest on the opposite side of the building.
Across the country, high school and college students also staged campus demonstrations and walkouts from classes.
In Oregon, demonstrators blocked traffic in downtown Portland, forcing a delay on two light-rail lines.
The crowd there grew to about 300 people, local reports said, including some who sat in the middle of a road to block traffic. Others burned American flags.
In Pennsylvania, hundreds of University of Pittsburgh students marched through the streets, with some in the crowd calling for unity.
The rallies followed protests overnight on Tuesday as voting results were being tallied, when at least one person was seriously injured in Oakland, California, where demonstrators broke store windows and set garbage alight.