So, we've had results projected in three of the six states voting:

• Michigan - BIDEN
• Missouri - BIDEN
• Mississippi - BIDEN

And we're waiting on:

• North Dakota
• Idaho
• Washington state

Voting in those last two doesn't stop for another 90 minutes.

We will also bring you a press conference in Philadelphia from Joe Biden, which we are expecting to happen soon.

Katty Kay
World News America presenter

Image source, Getty Images

If American girls are looking for a role model in the Oval Office, they will have to wait another four years.

The Democrats started this race, way back when Neanderthals still roamed the Earth it sometimes feels like, with a host of non-white, non-male candidates. One by one they dropped out.

If you want change in America in 2020, it seems, you are better off going with a white man in his 70s.

Warren referred to sexism in her farewell address. It's not the same sexism Hillary Clinton encountered when she first ran in 2008.

It is more subtle today, but Warren is right, there is still sexism.

I wish I could say I was surprised. (Though the survey's other finding that one third of the world's men think it's acceptable for a man to beat his wife did shock me. Really guys?)

So electability, it turns out, is code for male. In America it is code for old, white, straight male.

When will that change?

Read Katty's piece in full

Joe Biden has won Michigan, the biggest prize of the night, where 125 delegates are up for grabs, says CBS.

That is a massive blow to Bernie Sanders, who won that state four years ago against Hillary Clinton.

If the former vice-president does as well as this next Tuesday, when some big states join the race, he could by then look unstoppable.

Image source, Getty Images

Leaning (once again) on some of his most loyal supporters, Joe Biden won seven out of 10 black voters in Missouri, according to exit polls from BBC's US partner, CBS News.

But Obama's vice-president also made inroads among groups won over by Sanders in 2016, including white voters. Last time around, Sanders beat Clinton among white voters but early projections show Biden edging Sanders out by 12 points - 53% to 41% - in this group.

But the most important factor for Missouri's voters may have been that magic word: electability.

For 62% of voters here, Biden was seen as the candidate with the best chance of beating President Trump. Just 32% said the same for Bernie Sanders.

Polls are now closed all across Michigan - the key state to watch in tonight's contests.

Anthony Zurcher
BBC North America reporter

The Florida primary is a week away, but already Joe Biden has his surrogates making appearances in the state to push for votes.

On Monday morning in Aventura, just north of Miami, former Secretary of State John Kerry and Congresswoman Debbie Wasserman Schultz made an appearance at a local strip mall to open a new Biden office - one of several in the area that are popping up thanks to a surge of new money flowing into the campaign after his Super Tuesday wins.

Cary Fleischman was one of a few dozen attendees who plans on supporting Biden both at the polls and by volunteering. He says he’s been for Biden from the start, although he had his doubts about the campaign after it struggled in the early states of Iowa and New Hampshire.

Now, however, he feels comfortable with the vice-president – and says that he’s a much better option than Bernie Sanders, particularly for older, retired voters like himself.

“Seniors don’t want a revolution,” he says. “Every time Bernie says he wants a revolution, he wants to change America, he wants to shake it up and cause some chaos, seniors step back a little bit and say maybe I should leave the room.”

While he’s looking ahead to Florida next week, Fleischman says he has one eye on the results in the Michigan primary tonight, given that he’s originally from there and it’s where he still spends his summer.

Four years ago, Sanders re-energised his primary campaign with a surprise victory over Hillary Clinton. This time, however, Flieschman says he thinks Biden will prevail.

“Last time there was great excitement about Bernie coming in and changing things,” he says. “Since then, I think the Democrats that I know, Democrats in Michigan, are saying we need to change Trump. We’re not so much interested in changing Michigan.”

He says he’s tired of the primary campaign and wants to start focusing on the general election. If enough voters in Michigan, Florida and elsewhere feel likewise - and, like Fleischman, decide it’s time to throw in there lot with Biden - they may get their wish.

Earlier we told you about their healthcare plans. Next up, education.

Joe Biden says he will increase funding for schools in low-income areas, and help teachers, including through a competitive-pay system. But he has not provided any costing estimates.

Bernie Sanders, on the other hand, has a 10-point plan, that includes an end to for-profit charter schools, minimum pay for public school teachers and - notably - eliminating all student debt. He would finance this with a tax on Wall Street.

Image source, Getty Images

Missouri, where 68 delegates are up for grabs, has now been called for former Vice-President Joe Biden, says CBS.

We don't yet know how many delegates Biden will win in Mississippi, but before tonight he had a small lead over Sanders.

OK, we've heard a lot about what unites Biden and Sanders - they're Trump antagonists, veteran senators, and older white men in their 70s.

But there are key policy differences and we will bring you a few of them in the next hour.

First up, healthcare insurance.

In the case of Bernie Sanders, this would be universal and government-run. The Vermont senator says this would cost about $30tn over a decade, but critics put a much higher price tag on it.

Mr Biden has stuck by President Barack Obama's Affordable Care Act, but has offered proposals to make coverage less expensive. He is, in fact, proposing to spend $750bn over 10 years to this end.

Read more on Sanders' spending plans on healthcare

Image source, Getty Images

As expected, Joe Biden has carried Mississippi.

The former vice-president was helped by African-American voters, who make up the majority of the Democratic electorate in this southern state. According to CBS exit polls, 74% saw him as the candidate who best understands the concerns of racial and ethnic minorities. Only about one in five said this about Sanders.

But Biden was also the favourite of white voters, and was the top choice among those looking for a candidate to unite the country.

Joe Biden is the projected winner in Mississippi where 36 delegates are up for grabs, according to CBS News. He is also leading in Missouri where the prize is 68 delegates.

Both states were expected to go for the former vice-president based on earlier polling.

Polls in Missouri, Mississippi and parts of Michigan have now closed.

Image source, Alamy

Voting ends in 10 minutes in North Dakota which ties Wyoming for the smallest nominating race in the continental US.

There are just 14 delegates on offer.

Sanders won the state by nearly 40 points over Clinton in 2016, but it’s shaping up to be a closer race this time around.

Forecasting site FiveThirtyEight has given Biden a slight (7 point) lead over Sanders.

The 11th debate of this marathon fight for the nomination will still take place on Sunday evening - but there won't be anyone there to watch it.

CNN, which will host the showdown in Arizona, has just announced that it has cancelled the live audience due to safety concerns around the coronavirus outbreak. It says both campaigns had requested the move.

The post-debate spin room - where spokespeople for the candidates desperately try to convince reporters that their person won - has also been axed.

At the last debate in South Carolina (back when there were SEVEN on the stage), a boisterous crowd played its part.

Jon Sopel
BBC North America Editor

President Trump is used to fighting from his bunker when a crisis arrives - and let's face it, the past three and a bit years haven't lacked drama. But the coronavirus is quantitatively and qualitatively different from anything he has faced.

But how do you hit a virus? Who's to blame? Who's the guilty party? Who do you tweet at? Covid-19 doesn't have a Twitter account.

And in the midst of a health emergency, what is sacrosanct for anxious citizens - and frankly investors on Wall Street - is reliable information, a consistency of message from the government about the risks and how they can be mitigated, and that information flow will be based on the best available scientific evidence. No other factors should intrude.

In the US, as the administration has scrambled to mount an effective response, the messages have been mixed. Not for the first time, the president has been contradicting his own advisers and medical experts. That has been a consistent feature of this presidency.

From the outset of the coronavirus outbreak, Donald Trump has sought to play down its seriousness and overestimate America's preparedness. He said the spread was under control. It isn't. He's said that the number of cases may soon go down to zero. They haven't, and it was not the advice he'd been given. He suggested that people with symptoms should go to work if they felt well enough. They shouldn't.

Read Jon's full analysis including his take on why America's threadbare welfare state could make the US particularly vulnerable.

Senator Bernie Sanders argues time and time again that he - alone - can mobilise young and new voters.

And it's a fact that the 78-year-old is uniquely popular with the young, but on Super Tuesday there was no evidence of a spike in this age group.

Mr Sanders has admitted that it was "not easy" mobilising the youth vote. Why is that?

The BBC's Helier Cheung explains in the link below why this was the case and what it may mean for the main event - the presidential election in November.

Read more: Why don't more young people vote?

Image source, Grace Wells

Image source, Getty Images

Primary season is long - contests are held across the country from February until June - but the Democratic nominee is likely to emerge earlier as candidates rack up delegates through each primary contest.

Unlike some countries with legally defined campaign periods - like the UK and France - US candidates can campaign for as long as they wish, so presidential campaigns typically last about 18 months from start to finish.

Democrats will name their official nominees for president and vice-president at the Democratic National Convention, held from 13 July to 16 July in Milwaukee, Wisconsin.

But if Joe Biden has a big night tonight followed by further success next Tuesday when big states join the race, it's possible he'll claim an unbeatable lead and become the de facto nominee.

Tara McKelvey
BBC News, Kansas City, Missouri

Today I’m here in Kansas City, Missouri, the place where I grew up, while Bernie Sanders and Joe Biden are battling for the state’s 68 delegates. Things started out rocky: Mayor Quinton Lucas was turned away at a polling station. Later he was able to vote, but he and others here saw the mix-up as part of a larger problem. “Even when you’re in a position of power, people still see the colour of your skin,” says Lena Berhane, 21, a St Louis University student. She and her sister, Sarah, are both voting for Sanders.

Across town a retired businessman says Sanders is his worst nightmare. “He’s attacking me,” he says, explaining that Sanders - at least in his view - opposes free enterprise and competition in the marketplace. If Sanders ends up as the Democratic nominee, he will vote for Trump instead.

Image source, Getty Images

What’s the difference between primaries and caucuses?

All the votes happening today are primaries, not caucuses. The difference? Caucuses are a convoluted process, where people gather for a few hours for a party meeting and vote publicly in stages. It requires quite a bit of commitment.

Primary voters, on the other hand, can just turn up at a polling booth and vote in secret. Then leave. As a result, participation will be much higher.

Want to know more? We've got you covered.