Thousands of supporters of incumbent US President Donald Trump chanted "this isn't over" and "stop the steal" at protests over the weekend.
After a nailbiting few days without a clear winner, Democrat nominee Joe Biden was declared the new President-elect on Sunday after coming from behind to win battleground Pennsylvania.
But Trump is yet to acknowledge Biden's victory, which has been called from news outlets including the New York Times and Fox News.
Instead, the current President has made unsubstantiated claims of voter fraud and launched legal action in several states.
On Saturday, Americans from Atlanta and Tallahassee to Austin, Bismarck, Boise and Phoenix took to the streets to protest, echoing Trump's claims and with some openly carrying guns.
In Atlanta, Georgia, where a winner is yet to be declared, demonstrators chanted "lock him up", "this isn't over" and "fake news!", according to AP.
About 1000 Trump supporters gathered outside the state Capitol building waving American flags and Trump banners.
Georgia is a long-time Republican stronghold, having not voted for a Democratic candidate since 1992, but in the 2020 election that could change.
Biden is currently 10,000 votes ahead on 49.48 percent and Trump on 49.27 percent with 98 percent of the vote counted.
Jordan Kelley, a 29-year-old from Murfreesboro, Tennessee, drove over three hours to attend the rally.
"There's election fraud going on here," he said.
"Even though I live in Tennessee, I'm an American, and I want to make sure Americans have a voice in the election."
Kelley told AP he believed Georgia's governor and secretary of state, who are both Republicans, had incorrectly counted the ballots to put Biden ahead.
He also plans to drive 10 hours to Washington next week to protest on the steps of the Supreme Court, where Trump has vowed to take his fraud case.
In Washington DC, AP reported anti-Trump protesters shouted "Loser! Loser!" as he returned from a golf outing on Saturday, where he learnt of Biden's victory.
The 74-year-old business magnate released a statement while he was still on the course, saying the election is "far from over".
"Joe Biden has not been certified as the winner of any states, let alone any of the highly contested states headed for mandatory recounts, or states where our campaign has valid and legitimate legal challenges that could determine the ultimate victor," he said, the Guardian reported.
As Trump drove by, protesters gave the finger to his motorcade and waved signs saying "Don't be a sore loser" and "Face Reality".
Barbara Perry, the presidential studies director at the University of Virginia's Miller Center, told AP Trump's rejection of loss represents something new in American political history.
"We typically haven't had a leader who loses the presidency who then tells his followers, 'This is false. This has been stolen from us'," Perry said. "Incumbent presidents have been mad, so mad they didn't go to the inauguration, but not like this, where they are leading those people to say this is fraudulent."
A couple of thousand pro-Trump demonstrators also gathered in at the Capitol in Harrisburg, Pennsylvania, which secured Biden the win when he gained the state's 20 electoral votes.
AP reported over 20 heavily armed men, some wearing camouflage, joined the rally protesting news organisations calling the win for Biden.
Bruce Fields, 66, who was there, said: "If we don't stop this today, it'll all be over".
"Otherwise, we can kiss freedom goodbye."
Other protests included a "Stop the Steal" rally in Salem, Oregon and a large gathering in Austin, Texas.
