Polls will be closing in five minutes in Vermont and Virginia - we'll bring you the results of exit polls, and the projected winners, as soon as possible after that.

We've just heard from a judge in Tennessee who has ruled that the districts hit by yesterday's deadly tornado can remain open for an extra hour.

The ruling affect's the state's second largest county, which contains the city of Nashville.

Five other so-called megasites, where anyone affected by the tornado can vote, will remain open until 20:00 (01:00GMT).

Marianna Brady
BBC News

Image source, Connor Crawford

A deadly tornado ripped through Tennessee late last night. At least 22 people have died and several buildings have been destroyed.

Tennessee is one of the states holding a primary today - in East Nashville, Connor Crawford and Maria Rogers were meant to vote at their local community centre, but found out this morning that it was closed due to partial damage and a power cut.

Image source, Connor Crawford

After researching how they could still vote, the pair took to Instagram to share details with their fellow Tennesseans: “NASHVILLE, if your voting location was affected by the tornado, ANY voter can cast their ballot at 800 Second Avenue South, 4th Floor.” Polls close in just over an hour there.

Connor said he was happy to still be able to cast his vote for Bernie Sanders.

Image source, Connor Crawford

Katty Kay
World News America presenter

The queue outside the early voting station in downtown Raleigh, North Carolina, was long last Saturday. It snaked around the corner. Polling station officials estimated 700 people had cast early ballots that day. That’s bad news for Joe Biden.

He’s had a bump out of South Carolina - so much so that a poll taken in nearby Virginia since Saturday gave the former vice-president a new big lead over Bernie Sanders. If the same very recent bump in support has happened in North Carolina, it won’t be reflected in all those early ballots, cast at a time when Mr Biden was still in the doldrums.

Not that everyone has come on board the Biden express. On Saturday we interviewed State Senator Dan Blue, who used to support Joe Biden but after his disappointing results in Iowa and New Hampshire, Mr Blue endorsed Mike Bloomberg.

I texted Mr Blue on Sunday evening to ask if he regretted his decision to abandon Biden. No second thoughts, he told me. If Mike’s campaign has made Joe stronger, then that’s a good thing. And he still thinks Biden has a lot to do before he can take on Trump and win.

Image source, Getty Images

After Virginia, North Carolina is the next big state to watch. Polls close in an hour, at 19:30 local time.

How many delegates? 110

Who will do best? It's quite a similar picture to neighbouring Virginia, and will also be worth following - it's close between Sanders and Biden.

Who could do well? Bloomberg was polling well here at one point but is drifting behind a little by now.

One piece of context: This will also be a battleground state in November. As with Virginia, watch the crucially important suburbs of cities like Charlotte and Raleigh. But watch who they vote for, and whether that person ends up becoming the nominee. The way the votes go here in November might help decide the election.

Across the US, polling stations can look very different. Super Tuesday voters have cast their ballots in schools, gymnasiums, fire stations, universities, funeral homes and theatres, to name a few.

Image source, Getty Images

Image source, Getty Images

Image source, Getty Images

Jane O'Brien
BBC News, Burlington, Vermont

Image source, Getty Images

They're feeling confident here in Vermont because it's pretty certain their senator Bernie Sanders is going to win here.

He has tremendous support here and I don't think that going to end any time soon.

But when it comes to the rest of the country, his supporters, even here, are nervous.

Because even though they believe that their man can carry the nation, they're not so convinced that others share that view.

Zhaoyin Feng
BBC Chinese, Fairfax, Virginia

At a polling station in Fairfax, Virginia, many voters told me they had opted for Joe Biden, even though the former vice-president wasn’t their first choice.

According to the statistical analysis website FiveThirtyEight, Biden’s support in the state was roughly 20% two days before Super Tuesday, trailing behind Sanders (25%).

However, after moderates Pete Buttigieg and Amy Klobuchar dropped out of the race and endorsed Biden, his polling number surged to nearly 40%, giving him a sizable lead on Sanders.

Betty Charles, 73, had supported Senator Amy Klobuchar, but she cast her vote for Biden on Super Tuesday, hoping he’d consolidate support from centrist voters.

"If I didn’t vote for Biden, it’s essentially a vote for Sanders," she says, calling Sanders's progressive policy proposals "impractical".

"I don’t need a teddy bear as president, but he’s [Sanders] so angry all the time," she added.

Image source, Getty Images

Polls will close in the first two states in an hour - Virginia and Vermont. Here's what to look out for from Virginia.

How many delegates? 99

Who will do best? This will be a really interesting one to follow. The vote could be split fairly evenly between Sanders, Bloomberg and Biden.

Who could do well? See above.

One piece of context: Watch the results in the Washington DC suburbs. This suburban vote will be crucial across the country in November's election (as it was in the 2018 mid-terms). How will the nationwide favourite, Bernie Sanders, perform there? Will moderates in the suburbs warm to him?

Sophie Long
BBC News, Los Angeles, California

I'm here at California State University - home to 26,000 students and a Bernie Sanders stronghold.

I ask his voters why they picked him, and they say it's because he's the only candidate that's talking to them.

They are students, they're concerned about student debt, but they also care about issues like immigration.

Everything for Sanders has changed in the last 24 hours - they say a day is a long time in politics.

But now we have Joe Biden surging in polls after his two moderate rivals ended their campaigns and backed him.

The problem for Joe Biden is that accessible voting - 24-hour stations, people voting since Saturday, the mail vote - means that 3.5m people - some 40% of voters - have already cast their ballots. And some of those votes have gone for Amy Klobuchar and Pete Buttigieg, who have now pulled out and back Biden.

Image source, Getty Images

We just mentioned that California's results might not be known for a long time. That's because, in short, there’s a lot of counting to do.

There are a whopping 20.5 million registered voters in America’s most populous state. The majority of them will mail in their primary ballots. In the 2018 midterms, more than 60% of California voters cast absentee ballots.

Unlike some other states, Californians can wait up until election day to take their votes to the post office, meaning that many ballots won’t reach officials for a few more days.

County officials have 30 days to count all ballots and audit the tally before California’s secretary of state certifies the results by 10 April.

In smaller or less competitive races, we should find out who wins pretty quickly. But for more contentious contests, results won’t be called until every vote is counted.

It could take days or even weeks until we know the definitive outcome.

States across four time zones are voting today (or five, if you count the territory of American Samoa.) This means the results will be staggered across the next few hours.

We’ll be aiming to bring you the projected winners from each state as soon as possible after polls close, thanks to our US partner network CBS. Here’s when those polls close:

19:00 EST (00:00 GMT - just over an hour)

Vermont

Virginia

19:30 EST (00:30 GMT)

North Carolina (there are 110 delegates available here, and it’s likely to be close)

20:00 EST (01:00 GMT)

Alabama

Maine

Massachusetts

Oklahoma

Tennessee

20:30 (01:30 GMT)

Arkansas

21:00 EST (02:00 GMT)

Texas (the biggest state to vote so far - the results may take a little longer)

Colorado

Minnesota

22:00 EST (03:00 GMT)

Utah

23:00 EST (04:00 GMT)

California (a huge 415 delegates available - full results may not be known for days)

The US primary campaign season is long, costly, and leads to relatively low turnout rates. So is this the best way to pick a contender to take on Donald Trump in November's election?

Anthony Zurcher
BBC North America reporter

After weeks of hype and speculation, we’re about to find out exactly what spending a few hundred millions of dollars can accomplish in a presidential nomination campaign.

After sitting out the first four contests, Michael Bloomberg is finally on the ballot in the 14 states participating in Super Tuesday. He’s attempted to short-circuit the traditional campaign route through Iowa and New Hampshire by blanketing the airwaves, online and voter mailboxes with campaign advertising.

It’s an unconventional strategy for winning a party nomination, but when your net worth is in the $60bn range, you have the luxury of being unconventional.

A few weeks ago, it seemed like everything was going according to plan for the former New York City mayor. Joe Biden, his closest rival for the pragmatic, moderate vote, was sinking. Bloomberg’s poll numbers were rising.

Then he took the debate stage and seemed stiff and unprepared for the onslaught from his rival candidates.

Image source, Getty Images

Since then, Biden has regained his footing, and Bloomberg’s poll numbers have sagged. On Tuesday Bloomberg acknowledged that a contested convention - which is what you get when no-one is a clear winner after all the primaries - is now his best shot of getting the Democratic nomination.

Bloomberg still has an opportunity to land a share of the convention delegates at stake on Super Tuesday, which would give him leverage in fractured convention. His chances of winning any states, however, have been greatly reduced. Arkansas, Tennessee and North Carolina are perhaps his best shots.

If he falls short there, and elsewhere, he might have to starting thinking about whether there are better ways to spend his money than on a long-shot presidential bid.

As per usual - whenever there's a vote going on, we love seeing shots of our four-legged friends joining their humans as they perform their civic duty...

Image source, Getty Images

Image source, Getty Images

Image source, Getty Images

Nick Bryant
From the Bloomberg camp, West Palm Beach, Florida

Many see this as billionaire entitlement: Mike Bloomberg using his wealth in an attempt to buy the presidency.

He entered this race because he thought Joe Biden was weak. He wanted to block the candidacy of Bernie Sanders.

The irony is that Biden has surged and that Bloomberg's continued presence in the race helps the man he entered to stop.

Marianna Brady
BBC News

Over the course of the year, a group of young people will share their opinions with us at the BBC as the US moves to elect its next president.

Today, we’re going to introduce you to some of our Democratic panelists in Super Tuesday states.

We asked our panelists to tell us something unique about where they’re from. The first is Peyton Forte, a 21-year-old student from North Carolina.

Do you know who you are voting for? If not, what will decide your vote?

I will be voting for Elizabeth Warren. Though Warren and Bernie Sanders have similar platforms, the problem with Bernie is that he has failed to offer a nuanced analysis of the privileges of whiteness. He instead pivots to the maintenance of socioeconomic class as America’s greatest sin. Bernie’s record on race at times has been frustrating and Warren does better with articulating the intersection of race and class.

What’s at stake in this election?

Honestly, I’ve never liked this question because it assumes that Trump’s racist rhetoric and hateful policies goes against everything America stands for. It is this willful ignorance that has adversely impacted people of colour in this country for generations because white Americans have struggled to come to terms with the fallacy of America’s inherent goodness. A Trump re-election is so threatening because Democrats have failed to accept that he represents a sizable population of this country.

What should someone outside the US know about your state that makes it unique?

North Carolina is home to 12 historically black colleges and universities (HBCUs), second-most by state in America. The majority of HBCUs have rich histories involving political activism and community organising, and serve low-income, first-generation Black students. These institutions are filled with young, Black, civically mindful young people who have the potential to influence the upcoming election in North Carolina.

An average of national polls shows the ups and downs of the Democratic field.

The most recent surge? Former Vice-President Joe Biden was treated to a spike after a strong performance in South Carolina's primary over the weekend.

Image source, Getty Images

Voters in 14 states are heading to polling stations across the US today, but Americans living far from home will also have their say on the Democratic nominee.

Today, Democrats abroad will cast their ballot, either by mail or at one of hundreds of voting centres around the world.

In total, Democrats Abroad will send 13 delegates to the Democratic National Convention in July.

The 2020 election marks the first time that Latinos will be the largest racial or ethnic minority in the electorate, with 32 million eligible voters.

Texas, a state with 5.6 million eligible Latino voters, is voting on Super Tuesday. We went there to find out why their vote is important and what they're looking for in a Democratic candidate.