"Let's give each other a chance," he said at an event in Delaware addressing those who did not vote for him.

Mr Biden defeated incumbent President Donald Trump following a cliff-hanger vote count after Tuesday's election.

Mr Trump has yet to concede and has not spoken publicly since his defeat was announced while he was playing golf.

Joe Biden has been elected the 46th president of the United States, achieving a decades-long political ambition and denying Donald Trump a second term after a deeply divisive presidency defined by a once-in-a-century pandemic, economic turmoil and social unrest.

Biden won the presidency by clinching Pennsylvania and its 20 electoral votes, after several days of painstaking vote-counting following record turnout across the country. The win in Pennsylvania, which the Associated Press called at 11.25am ET on Saturday with 99% of the votes counted, took Biden’s electoral college vote to 284, surpassing the 270 needed to win the White House.

The result makes Mr Trump the first one-term president since the 1990s. His campaign has filed a barrage of lawsuits in various states but election officials say there is no evidence that the vote was rigged against him, as he has claimed.

Spontaneous celebrations erupted in major cities after media outlets announced Mr Biden's victory on Saturday. Disappointed Trump supporters demonstrated in some cities but there were no reports of incidents.

Biden: 'We have to stop treating our opponents as enemies'

Addressing cheering supporters in a car park in his hometown of Wilmington, Mr Biden said: "I pledge to be a president who seeks not to divide, but to unify; who doesn't see red states and blue states, only sees the United States."

Mr Biden - who has won more than 74 million votes so far, the most ever for a US presidential candidate - hailed the "diverse" support he gathered during the campaign, and thanked African-American voters in particular.

But he also reached out to Trump supporters directly.

"It's time to put away the harsh rhetoric, lower the temperature, see each other again, listen to each other again," Mr Biden said, without mentioning his rival in the election. "And to make progress, we have to stop treating our opponents as enemies."

Kamala Harris savoured the moment she became the first woman, and the first black and Asian American, to be vice-president-elect, with a very hearty laugh.

In a video posted to her social media she shares the news with President-Elect Joe Biden: "We did it, we did it Joe. You're going to be the next president of the United States!"

Her words are about him but the history of the moment is hers.

Just over a year ago, as the senator from California hoping to win the Democratic nomination for presidency, she launched a potent attack on Joe Biden over race during a debate. Many thought it inflicted a serious blow on his ambitions. But by the end of the year her campaign was dead and it was Mr Biden who returned the 56-year-old to the national spotlight by putting her on his ticket.