Victorious Joe Biden and his team have launched their official transition website and social media channels, laying the groundwork for taking over as US president.
The team has spent months making the arrangements and on its website, BuildBackBetter.com, outlined a "seven-point plan to beat COVID-19", and said: "We aren't just going to rebuild what has worked in the past. This is our opportunity to build back better than ever."
In a statement, Mr Biden's team said: "The crises we are facing are severe - from a global pandemic to an economic recession to racial injustice to the climate crisis. Our work continues full speed today."
And in their first Tweet, the Biden transition team said: "We stand together as one America. We will rise stronger than we were before."
He also has "agency review teams" to consider how he wants to run the country.
The statement continued: "Across the board we will continue laying the foundation for the incoming Biden-Harris administration to successfully restore faith and trust in our institutions and lead the federal government."
Donald Trump - who was back playing golf in Sterling, Virginia on Sunday - is still refusing to concede and has fired off a barrage of tweets with unfounded claims about electoral fraud - including that tens of thousands of votes were illegally cast.
In one post, using capital letters, he declared: "I WON THE ELECTION, GOT 71,000,000 LEGAL VOTES" - Twitter immediately flagged it as misleading.
In Mr Trump's latest tweets, he appeared to quote a law professor as saying: "We're seeing a number of affidavits that there has been voter fraud. We have a history in this country of election problems."
He is the first incumbent president to lose re-election since Republican George HW Bush in 1992.
His victory followed more than three days of uncertainty as election officials sorted through a surge of mail-in votes that delayed processing, but Mr Biden crossed the winning threshold of 270 Electoral College votes with a win in Pennsylvania.
"I sought this office to restore the soul of America," he said in a prime-time victory speech not far from his Delaware home, adding: "and to make America respected around the world again and to unite us here at home".
Kamala Harris made history as the first black woman to become vice president, and she is also the highest-ranking woman ever to serve in government, four years after Mr Trump defeated Hillary Clinton.
The California senator introduced Mr Biden "as a president for all Americans" and nodded to the historic nature of her ascension to the vice presidency.
She said: "Dream with ambition, lead with conviction and see yourselves in a way that others may not simply because they've never seen it before.
"You chose hope and unity, decency, science and, yes, truth - you ushered in a new day for America."