Tensions are sky-high heading into the 2020 election, and those combustible forces will be inflamed once the winner of the presidential race is officially announced.

Businesses in major American cities have already started to board up their storefronts in anticipation of potential riots from the election. Law enforcement agencies across the country are also preparing for the worst-case scenario, which could mean widespread violence stemming from the presidential election.

"I don't think we've seen ­anything like this in modern times," Andrew Walsh, a deputy chief with the Las Vegas Metropolitan Police Department, told The Washington Post. "When you look at previous elections, there's always been the concern when you have large crowds . . . we know [that] can be a target for someone who has an agenda."

Walsh is concerned that the results of the race likely won't be available on election night, which could exacerbate the already bellicose situation.

"We just don't know how long this is going to take, or what this is going to look like, once this is over ... and no matter who wins, somebody's not going to be happy," said Walsh, who heads the Las Vegas Police Department's homeland security division.

The New York City Police Department said it would dispatch officers at each of the city's 1,201 polling locations on Election Day.

"It is no secret that this election is more contentious [than] in years past," said NYPD Chief of Department Terence Monahan. "For that reason ... our plan also includes the ability to respond to any type of incident that may occur."

Washington, D.C., canceled days off for police officers starting this weekend. The nation's capital "spent $100,000 on less-than-lethal munitions and chemical irritants for riot control to replenish a stockpile depleted by clashes over the summer," The Washington Post reports.

"It is widely believed that there will be civil unrest after the November election regardless of who wins," said D.C. Police Chief Peter Newsham. "It is also believed that there is a strong chance of unrest when Washington, D.C., hosts the inauguration in January."

According to Chicago Police Superintendent David Brown, the department has canceled all days off for its force in November.

Brown said police and emergency responders are training for "whatever scenario happens on Election Day."

"Many cities across the country are doing similar planning," Brown said. "We are all in conversations with our counterparts across the country about what we might expect, but everything is uncertain, and so we're trying as best we can to anticipate any hazard that might happen, including a weather hazard, snow might happen in our city, along with anything related to protests, embedded agitators that might loot or cause violence or destroy property."

The Boston Police Department canceled officers' time off around the election "to provide sufficient public safety."

Boston Mayor Marty Walsh said his administration is planning for potential violence stemming from the election.

"What is kind of alarming to me is that the preparation that we're putting into this election we've never had to put into an election before," Walsh said. "I certainly wasn't asked in 2016, 'What's your safety plan for Election Day?'"

Austin Police Department Assistant Chief Joseph Chacon said the department would be on "tactical alert" during the week of the election, and that every officer would be made available to respond to civil unrest.

As early as this weekend, the Texas National Guard plans to send up to 1,000 troops to five cities: Austin, Dallas, Fort Worth, Houston, and San Antonio.

The Beverly Hills City Council approved "an additional $4.8 million for supplemental police and security services in anticipation of the potential civil unrest around the presidential race," including "hiring two private armed security firms," according to the Beverly Hills Courier.

For the first time in Denver's history, the city is establishing a police command center in preparation for potential post-election unrest.

Denver's Public Safety Director Murphy Robinson said he is aware of two planned protests on Election Day with upwards of 2,000 people each.

A report from The Federalist states that insurgent groups against President Donald Trump have already planned Election Day turmoil to "make sure Trump leaves the White House."

"[W]e're making plans to be in the streets before the polls even close, ready to adapt and respond to whatever comes our way," the group Shut Down DC said on its website. The purpose of the gathering is to "be together to process our feelings of hope, anger, fear and exhaustion as a community."

The New Jersey Department of Homeland Security and Preparedness issued a threat assessment in September that warned about "threats from domestic extremists and foreign adversaries have emerged due to the COVID-19 pandemic, anti-government sentiment, nationwide civil unrest, and various forms of disinformation. These threats will begin to converge with the Presidential election in November in a manner not previously experienced by our nation."