Joe Biden has won the race to become the next US president, defeating Donald Trump following a cliff-hanger vote count after Tuesday's election.
The BBC projects that Mr Biden has won the key battleground of Pennsylvania, propelling him over the 270 electoral college vote threshold required to clinch the White House.
The Trump campaign has indicated their candidate does not plan to concede.
Mr Biden said it was now time for America to "unite and heal".
"With the campaign over, it's time to put the anger and the harsh rhetoric behind us and come together as a nation," he said.
Record turnout in the face of "unprecedented obstacles", he said, showed democracy "beats deep in the heart of America".
His running mate, Kamala Harris, is set to become the first woman vice-president.
The BBC's projection of Biden's victory is based on the unofficial results from states that have already finished counting their votes, and the expected results from states like Wisconsin where the count is continuing.
His projected wins in Pennsylvania and now also Nevada take him to 279 electoral college votes.
The election has seen the highest turnout since 1900. Mr Biden has won more than 74 million votes so far, the most ever for a US presidential candidate.
Offering his congratulations, former President Barack Obama, with whom Mr Biden served two terms as vice-president, said: "I know he'll do the job with the best interests of every American at heart, whether or not he had their vote."
Biden supporters have been gathering in the streets on New York and other cities to celebrate victory.
How has Trump reacted?
Mr Trump has drawn more than 70 million, the second-highest tally in history.
President Trump had falsely declared himself the winner of the election when vote counting was unfinished. He has since alleged irregularities in counting, but has not presented any evidence of election fraud.
After Mr Biden was projected to win he remained defiant, saying Mr Biden was "falsely posing as the winner" and insisting the election was "far from over".
His campaign has filed a barrage of lawsuits in various states.
The response from senior Republicans has been muted. Republican Party Chairwoman Ronna McDaniel tweeted that "the media doesn't decide who wins elections, voters do". But Senator Mitt Romney, a critic of Mr Trump, congratulated Mr Biden and Ms Harris. He said he and his wife "know both of them as people of good will and admirable character".
■ 'Let's work together!' - How world reacted to Biden win
The election was fought as coronavirus cases and deaths continued to rise across the United States, with President Trump arguing a Biden presidency would result in lockdowns and economic gloom. Joe Biden accused the president of failing to impose sufficient measures to control the spread of Covid-19.
At the age of 78, Mr Biden will be the oldest president in American history.
Joe Biden's projected victory after four days of painstaking vote-counting is the denouement of an extraordinary campaign, conducted during a devastating pandemic and widespread social unrest, and against a most unconventional of incumbents.
In his third try for the presidency, Mr Biden found a way to navigate the political obstacles and claim a win that, while perhaps narrow in the electoral college tally, is projected to surpass Mr Trump's overall national total by at least four million votes.
With his projected victory, Joe Biden becomes the oldest man ever elected to the White House. He brings with him the first woman vice-president, whose multi-ethnic heritage carries with it numerous other firsts.
Mr Biden can now begin the arduous task of planning the transition to his new administration. He will have just under three months to assemble a cabinet, determine policy priorities and prepare to govern a nation facing numerous crises and sharply divided along partisan lines.
Joe Biden has been dreaming of the White House for most of his 50 years in the public arena. With this prize of a lifetime, however, come the challenges of a lifetime.
What happens now?
Usually the losing candidate concedes but Mr Trump has vowed to contest the election results on several fronts.
A recount will be held in Georgia, where the margins are tight, and Mr Trump wants the same in Wisconsin. He has also vowed to take legal action to the Supreme Court, alleging voting fraud.
If the election result is challenged, it would require legal teams to challenge this in the state courts. State judges would then need to uphold the challenge and order a recount, and Supreme Court justices could then be asked to overturn a ruling.
BBC