Shop windows are covered in boards, police are patrolling city streets and a new fence has been erected around the White House in anticipation of civil unrest.

This is not a typical US presidential election.

Even without the coronavirus pandemic, the showdown between President Donald Trump and Democratic leader Joe Biden was set to aggravate an increasingly polarised America.

But 2020 has not been an ordinary year.

Americans are choosing their next president against a backdrop of record-breaking COVID-19 deaths, economic turmoil and boiling racial tensions triggered by police brutality.

No matter who wins, violence is a real possibility.

US President Donald Trump said “there is no reason” for Americans to start riots after the winner is declared.

But if this were to happen, he said “Democratic cities” would be at the centre of it all “because of weak leadership”.

“I think it’s very sad when stores are boarded up, because a piece of glass is very expensive and plywood doesn’t cost very much,” Mr Trump said on Wednesday morning (Australian time).

On Monday, federal authorities re-erected a “non-scalable” temporary fence around the White House – the same type that was installed during anti-racism protests sparked by the killing of George Floyd.

The fence is labelled “non-scalable” because its panels are about 2.5 metres tall, and made of a metal grate comprising of tiny diamond-shaped openings that are too small to allow a toehold.

The barricade covers the White House grounds, including the Ellipse and Lafayette Square, blocking citizens from getting closer than 137 metres to the complex.

An outline of where the new fence will be installed around the White House. Photo: Twitter

NBC News White House correspondent Geoff Bennett tweeted on Sunday that 250 national guardsmen had been put on standby.

Shopkeepers have been taking matters into their own hands as a precaution.

The entire neighborhood surrounding the White House is preparing for mass unrest: boards, chains, fences, and barriers. This is insane. pic.twitter.com/baXj3RD2Cf

— Christopher F. Rufo ⚔️ (@realchrisrufo) October 30, 2020

Is this a US election like no other? Well it’s the first any of my American colleagues can recall the nation’s capital preparing for polling day by boarding up the shop fronts around the White House. pic.twitter.com/WmLxrRojKx

— Paul Danahar (@pdanahar) October 30, 2020

Much of downtown Washington has been boarded up over fears of violence after the presidential election on Tuesday. Shop owners – any many Americans we’ve spoken to – fear riots and disorder whatever the outcome. pic.twitter.com/7RcHyyv0YA

— Ben Kentish (@BenKentish) October 31, 2020

In an email sent last week, George Washington University urged students to be prepared for possible election-related disruptions “near the campus in Washington DC, and to stockpile a week’s supply of food and medication”.

Last month, Washington news station WUSA9 revealed the DC Metropolitan Police Department had bought more than $US100,000 worth of tear gas canisters before the election.

“In law enforcement circles, it is widely believed there will be civil unrest after the November election regardless of who wins,” DC Police Chief Peter Newsham told DC Council members.

“Now is not the time to restrict the police department’s ability to effectively deal with illegal rioting.”

Meanwhile in Chicago on Monday, a news photographer posted a video to Twitter of heavily armed National Guard vehicles cruising the streets.

Spotted the National Guard coming into Chicago and pulling into McCormick Place. pic.twitter.com/h6Ekzb1Vue

— George Mycyk NBC 🇺🇦 (@GeorgeMycykNBC) November 2, 2020

The Illinois Guard has reportedly refused to offer an explanation for the unusual military presence.

Gun sales have leaped to record numbers, too.

According to a report from The Los Angeles Times, Americans from all demographics – not just long-time gun owners – helped set a new national record for the biggest spike in gun sales in 2020.

On Thursday, Walmart asked all of its stores to move firearms and ammunition to a secure storage area over fears of “isolated civil unrest”, but the retailer giant reversed the decision a day later.

Oregon’s capital city, Portland – the site of regular mass protests against police brutality and racial injustice since the death of George Floyd – is a particular worry.

On Saturday, police declared a riot after protesters were allegedly spotted damaging businesses and hurling objects at police officers.

Anti-police protesters clashed with federal police as they marched through Portland, Oregon, last month. Photo: Getty

Election disputes

There are serious concerns Mr Trump will either claim victory prematurely if it looks like he’s ahead on election night, or that he will refuse to accept the result if Mr Biden wins.

For months, the President has been sowing doubt about the electoral system, falsely claiming that mail-in voting enables fraud and will result in a “rigged election”.

Despite efforts by Twitter to label or remove tweets “that could undermine faith” in the election process by suggesting “election rigging” or “ballot tampering”, Mr Trump has created a volatile political environment.

More recently, he angered Democrats by voicing support for the “patriots” who surrounded and intimidated a Biden-Harris campaign bus in Florida.

Adding to this tension is growing speculation that the election result will not be immediately known due to COVID-related delays and the arduous task of processing a record number of mail-in ballots.

More than 91.6 million Americans had already voted by November 1.

If it’s a tight race, it could take election officials days to count the backlog of mail-in ballots before the winner is announced.

After months of clashes between anti-racism protesters and far-right groups across the nation, the White House is preparing for things to get messy.