Prime Minister Jacinda Ardern was among many leaders around the world to congratulate the Democratic ticket.
The win is objectively impressive for the Democrats.
They have brought down an incumbent - a rare and difficult feat. In modern times, only Jimmy Carter (1977 - 1981) and George Bush snr (1989 - 1993) served a full term and then were defeated in their bid for a second.
Biden has achieved his career peak at 77 and Harris is the first female vice-president and the first of Jamaican and Indian descent.
A likely end Electoral College tally of 306 would equal Trump's result in 2016 and once again the Democrats showed they could triumph in the EC and popular vote at the same time. A Republican has only managed that once in the past eight elections.
In a hare and tortoise vote-counting race, Trump's early advantage with in-person votes got overtaken in agonisingly slow fashion over days by Biden's late-counted mail ballots.
A massive voter turnout, increased use of mail ballots and legal challenges were the chief reasons for the drip-feed of results. Biden took double-digit leads in the battlegrounds of Pennsylvania, Arizona and Nevada and a small but remarkable advantage in Georgia - a southern state no Democrat has carried since Bill Clinton in 1992.
The party doesn't appear to have reached its goals on gaining control of the Senate and expanding its numbers in the House of Representatives. Republican congressional incumbents did better than expected. But Senate control is still up in the air with two seats in Georgia going to runoffs on January 5.
More than 74 million people voted for the Democrats - the most any US presidential ticket has recorded and about 4 million more than voted for Trump.
The President's vote tally with Mike Pence was also more than what they achieved in 2016. Trump, with 47.7 per cent of the popular vote was up by 1.3 per cent on four years ago, while Biden out-performed Hillary Clinton by 2 per cent.
The Democratic "Blue Wall" of Wisconsin, Michigan and Pennsylvania was rebuilt. Aside from Georgia, Arizona was another Republican red state to turn blue for the first time in decades. Texas and North Carolina were competitive.
The combination of Biden and Harris was competitive in the Rust Belt and Sun Belt, attracting more white voters, particularly in suburbs, than was the case in 2016, and getting strong support from non-white voters in major cities.
Democrats showed that they can compete anywhere with urban and suburban-based voters - serving notice that Republican states in the south will increasingly be in play in the future.
All this has been overshadowed by Trump's fate and the huge challenges ahead, but after the nightmare of four years ago, Democrats can at least sleep easier.