s millions of Americans converge to vote in one of the most contentious elections in U.S. history, police forces across the nation are taking unprecedented steps to brace for potential disruption at the polls and post-election violence.

“It’s fair to say the police are preparing in ways they never would have had to for Election Day,” says Chuck Wexler, executive director of the Police Executive Research Forum, a Washington-based think tank. “This year is unlike any other year.”

With longer lines at poll sites due to social-distancing restrictions and short tempers after months of dealing with multiple national crises, from the pandemic to the economy, it wouldn’t take much to ignite a conflict. Wexler says he can see clashes erupting if someone is not wearing a mask inside a poll site or if a voter’s eligibility to cast a ballot is called into question. “Because this election is more important than it has been in years, you’re going to have people that are going to have frayed nerves,” Wexler says. “You can easily have some kind of confrontation.”

In New York City, police officers will be stationed in more than 1,200 […]