This US election looks set to come down to the results in three states which traditionally form a 'blue wall' across America's rust belt.

In 2016 the states of Pennsylvania, Michigan and Wisconsin all swung to Donald Trump.

But in 2020 it's going Joe Biden's way with victory projected in Michigan and Wisconsin, even though Donald Trump is threatening legal challenges.

So what's the view to the count in each of the crucial states?

Sally Lockwood, news correspondent, in Michigan

As Joe Biden's lead grew in Michigan so did the tension in the counting hall in Detroit. You could see it even before entering the building. A heated group gathered at the entrance were being told to stand back by the police.

One official warned me the atmosphere was "dicey" - explaining the crowd of people trying to get in were "poll watchers" or "poll challengers" as they're known. These people monitor the counting and are often from the opposing political party. "There's a lot of posturing going on," he said.

At a second internal entrance to the counting hall, another group is also trying to get access. Some are angry and a few are beginning to shout. In the short time since we've been here police have escorted at least three people out of the hall to cheers and clapping. They're being thrown out over accusations of intimidating vote counters.

Officials have started covering windows in the hall to try to prevent the crowd outside from disturbing the counting. Some responded by banging on the windows and people from the opposing side have been tearing the covers down.

William Hartmann from the Wayne County Board of Canvassers is here to monitor the integrity of the election for the Republicans. He explains that all parties have poll watchers in the room.

"Every political group is allowed 134 challengers present," he says.

"They say that we're at capacity now and those people are still outside. The Republicans can come in and monitor. The issue is they're not counting the people coming in and going out, so how can you know how many people are in and how many people are out?"

Joe Biden's lead is now insurmountable but the Trump campaign has filed a legal challenge at a Michigan court.

Mr Trump is alleging wrongdoing in a state that offers Mr Biden a path to power without the need for Pennsylvania.

We're seeing first-hand how Mr Trump's rhetoric and legal action is fanning the division and distrust we feared following this election result.

James Matthews, news correspondent, in Milwaukee, Wisconsin

Delay.

That's the guaranteed effect of Donald Trump's demand for a recount in Wisconsin. Implications beyond that will come down to the numbers, recounted.

This state of razor-thin electoral margins is no stranger to a recount. Mr Trump faced one when he triumphed here, against the odds, in 2016.

He's not asking for anything beyond his entitlement. An 'aggrieved' candidate is entitled to request a recount if he/she is within a percentage point of the election winner.

The rules make it clear.

What's less clear are the exact grounds for challenge.

A statement from the Trump 2020 campaign manager Bill Stepien spoke of "irregularities in several Wisconsin counties which raise serious doubts about the validity of the results", without detailing what those were.

Guidance from the Wisconsin Electoral Commission speaks of a recount being finished by the end of the first week in December.

It is a timeline to trouble this country as it chases a result and a president.

Mark Stone, news correspondent, in Philadelphia, Pennsylvania

They are still counting in Pennsylvania.

They have hundreds of thousands of ballots to get through; many of them absentee ballots legitimately cast in good time and yet now cast as illegitimate by the president.

His election night statement was explicit and built on his characterisation of postal ballots as vulnerable to fraud.

Hours later his son Eric and lawyer Rudy Giuliani arrived in Philadelphia.

Mr Giuliani said: "Not a single Republican has been able to look at any of these mail ballots…they could be from Mars as far as we're concerned!"

The core of their argument was that Republican election monitors had not been allowed to monitor counts (they provided no evidence of this) and so they couldn't be sure that fraud hadn't taken place.

But those at the coal face of the counts aren't hiding their contempt.

"Counting votes cast on or before election day by eligible voters is not cheating. It's democracy," Al Schmidt told me. He is one of three election commissioners for the city and is a Republican.

North of Philadelphia in Doylestown we met Chris Frey, once a Republican but now a so-called never-Trumper.

"He basically said 'stop counting the ballots now because I am ahead'. That's not how democracy works," he said.

But a block away, evidence of the country-wide divide.

Franco Federico, a local restaurant owner, believes the president's claims of fraud.

"I certainly do believe him. He is not here to 'fraudulent' any election. Obviously he's fighting through because he is doing it for the better of this country," he said.

Pennsylvania was Donald Trump's biggest prize four years ago.

He has tried to claim it again. The courts will decide if he has a case - when he provides the evidence.