Anti-Trump protesters gathered outside the White House on Friday as Democratic hopeful Joe Biden appears close to winning the presidency.
Vote counting is ongoing and a victor cannot be announced yet.
But Biden is ahead of Trump in the remaining battleground states.
In a speech on Friday, Biden said he is set to win the election "with a clear majority, with the nation behind us."
But recognising growing tensions, he urged Americans to "put anger and demonisation behind".
Prosecutors on Friday charged two men who were carrying weapons near the Pennsylvania Convention Center, where ballots from the election are still being counted.
The incumbent President meanwhile, warned Biden not to declare himself the winner.
Trump has made repeated unsubstantiated claims of voter fraud and his team have launched several legal challenges.
Trump's supporters have protested outside polling stations.
New York and the Black Lives Matter movement, meanwhile, decided to celebrate Biden lead on Friday, despite the vote being too early to call.
Alaska, Georgia, Nevada and Pennsylvania are still counting ballots.
George Floyd's death three year anniversary: has anything changed?
Go to video
President Biden authorises sanctions against Sudan
Go to video
USA: African-American nationalists accused of acting for Russia
For BLM's Patrisse Cullors, art is both vocation, salvation
Summit for Democracy: Zambians attend virtual event
Harris visits Ghana's president, promises aid, investments