The US election has arrived.

And as political pundits and punters around the world tune in to watch it unfold, it’s likely they’ll be greeted by some surprising patterns.

Coronavirus has changed everything about this US election, including how votes are cast – Democrats have voted early in huge numbers, while Republicans like to go the more traditional route – voting on election day.

There are 50 American states and 50 different ways for counting votes.

Some states pre-count the early votes and others will only begin to count them on election day, with Pennsylvania a notable example.

Because of the huge early vote count this year, these rules are expected to create a confusing phenomenon called ‘red mirage’ and ‘blue mirage’.

And each could have dramatic consequences for the candidates and may lead to President Donald Trump declaring victory early.

Blue Mirage

The states that count early votes before election day are likely to show a huge swing towards former vice president Joe Biden early on, creating a blue mirage across key battlegrounds including Florida, North Carolina, Ohio and Iowa.

This will make Republicans nervous.

“We will get real-time data with contemporaneous in-person voting in Florida, Arizona and North Carolina on the day,” said senior fellow at the United States Studies Centre Bruce Wolpe.

“They are pivotal states.”

Other key states that Mr Trump won in 2016 but could be at risk of losing include Texas, Iowa and Ohio – which also all process their early votes before the big day – and could help add to the blue mirage effect.

Red mirage

Three key states – Pennsylvania, Michigan and Wisconsin – all start counting their early ballots on election day.

Of these, Pennsylvania is giving everyone the biggest headache.

It’s a big battleground for both candidates and the vote-counting could continue for days after the Democrats recently won a victory in the US Supreme Court to have mail-in ballots counted three days after the election as long as they are postmarked for November 3.

“To win the election, Trump has to carry one of Pennsylvania, Wisconsin, and Michigan and not lose anything else,” Mr Wolpe said.

“If Trump holds all key states – North Carolina, Georgia, Florida, Texas, Arizona – and the count is in doubt in Pennsylvania he will still have a shot at it.

“We could have martinis at 5pm or we could be here for two weeks.”

It will go one of two ways, he said.

“By 4pm (AEDT) on Wednesday, it will be clear if Biden is in a strong position or the vote count is so muddled it’ll go on for some days and there will be legal challenges,” he said.

It’s D Day for Donald Trump. Photo: Getty

Professor Wesley Widmaier said it was the blue mirage punters should watch closely, as it could hold real insight into how the day will unfold.

“The blue mirage states are states that we look to give us real information early. They will show us real data,” he said.

“The red mirage, Pennsylvania in particular, Trump will be fighting over if they are going to declare an early victory as they’ve said.”

Mr Trump’s campaign team has made it clear if it thinks it has enough swing states in the bag, it will declare victory.

This has raised concerns we could see another Bush v Gore, where the Supreme Court stepped in to halt a vote recount in Florida, effectively handing the nomination to Mr Bush.

“I think this will end up in the Supreme Court,” President Trump said in late September.

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If there is confusion over the count in Pennsylvania, and everything else is tight, we could possibly be waiting till January, Professor Widmaier said.

He said the Gore v Bush decision was not meant to be used as legal precedent, but because the Supreme Court is stacked in Mr Trump’s favour, there was no vote to hold them to account.

“When you’re on 6 to 3 judges in your favour, you can make it up as you go. There’s less need to have that caution,” he said.

“Politics is not a pillow fight.”

If Mr Trump declares himself an early winner in Pennsylvania and the Supreme Court backs him, that ruling could then be challenged in the House, meaning the decision of who rules the United States could be in limbo until January, he said.

“I would emphasis, we want to look North Carolina, Florida, and maybe Georgia early on. They could be good indicators. If Biden gets Florida and North Carolina, Pennsylvania might not even matter.”