As Donald Trump threatened to sue over what he alleged was a "stolen" election, his supporters in some states gathered to demand counts be stopped – while in others they insisted all ballots be counted.
After the president claimed, without evidence, that mail-in ballots in states such as Michigan had fraudulently favoured opponent Joe Biden, fans of Mr Trump appeared at the TCF Center in Detroit shouting "let us in" and "stop the count".
Local media reported raucous scenes as Republican counters attempted to enter the building, alleging they were being unfairly kept out – a claim denied by local Democrats also kept outside.
In stark contrast, pro-Trump demonstrators showed up at counts in Nevada and Arizona demanding that all votes be counted.
Outside the counting centre in Maricopa County, Phoenix, a crowd of Republican supporters, some armed, gathered shouting "count the votes" and "Fox News sucks", after the right-wing TV network earlier called Arizona in Mr Biden's favour.
Observers from both parties were inside the election centre as ballots were processed and counted, and the procedure was live-streamed online at all times.
Several sheriff's officers blocked the entrance to the building, and the vote-counting went on into the night, Maricopa County Elections Department spokeswoman Megan Gilbertson said.
Two top county officials — one a Democrat, the other a Republican — issued a statement expressing concern about how misinformation had spread about the integrity of the election process.
"Everyone should want all the votes to be counted, whether they were mailed or cast in person," said the statement signed by Clint Hickman, the Republican chairman of Maricopa County Board of Supervisors, and Democratic supervisor Steve Gallardo. "An accurate vote takes time. This is evidence of democracy, not fraud."
Meanwhile thousands of Trump opponents took to the streets in cities across the US demanding a complete tally of ballots.
In Portland, Oregon, which has been a scene of regular protests for months, governor Kate Brown called out the National Guard as demonstrators engaged in what authorities said was widespread violence. Protesters in Portland were demonstrating about a range of issues, including police brutality and the counting of the vote.
"It's important to trust the process, and the system that has ensured free and fair elections in this country through the decades, even in times of great crisis," Ms Brown said in a statement. "We are all in this together."
In New York, hundreds of people paraded past boarded-up luxury stores on Manhattan's Fifth Avenue, and in Chicago, demonstrators marched along a street across the river from Trump Tower.
Similar protests — sometimes about the election, sometimes about racial inequality — took place in at least a half-dozen cities, including Los Angeles, Houston, Pittsburgh, Minneapolis and San Diego.
Earlier, the Republican campaign filed a suit in a bid to halt the count in Michigan, demanding the Democratic secretary of state allow in more inspectors.
Michigan attorney general Dana Nessel, a Democrat, insisted both parties and the public had been given access to the tallying, "using a robust system of checks and balances to ensure that all ballots are counted fairly and accurately".