Live election updates: Results for key races in New York, New Jersey and Connecticut

A historic election that saw an incumbent president drop his campaign, a woman rise to the top of the Democratic ticket and multiple assassination attempts against the Republican candidate will come to an end on Nov. 5.

But the outcome may not be known on election night.

It took four days for the race to be projected for President Joe Biden in 2020 as mail-in voting expansions, and other changes made to help Americans participate during a global pandemic, delayed counting in several key states.

An especially tight race, as expected this year, can make it even more difficult to project a winner in the hours after polls close, experts told ABC News.

For more on the paths to victory and when we might know the winner, watch this story from Joe Torres.

Joe Torres on the paths to victory and when we might learn who is the next president

The Board of Elections identified a problem happening at some election sites in Queens on Tuesday.

At P.S. 164 in Flushing, voters reported issues with scanning their ballots. We are told machines would spit the paper ballots right back out and voters were left, in some cases, handing in paper ballots.

The Board of Elections says an emergency bin was used. It is unclear how long exactly this went on, but the board says every vote will be counted.

The BOE issued a statement saying "technicians were immediately dispatched, and corrective measures were undertaken. In an abundance of caution, we had all 290 sites in Queens inspected."

Anthony Carlo has the latest from Flushing, Queens.

Voters have not been impacted beyond additional attempts to scan their ballot or have it placed in the emergency bin as is protocol, the BOE said.

At P.S. 36 in the St. Albans area of Queens, Eyewitness News found a steady line of voters late Tuesday morning but that line we are told was not moving as well earlier when the site first opened.

A poll worker tells us one of the computer tablets was improperly configured for early voting. A tech had to be sent out by the Board of Elections to fix the issue. But site workers say this caused a problem for about an hour and a half as they could not "service the voter."

For the better part of 2023 and 2024, President Joe Biden plotted a course to Nov. 5, 2024. As the incumbent, the veteran politician was the presumptive Democratic nominee, clinching enough delegates in March, and locked in a tight race with former President Donald Trump.

But instead of spending Election Day preparing for an evening speech, the president's daily schedule is empty beyond his daily briefing by aides: No public events.

The president and first lady Jill Biden will spend election night watching the election results in the White House residence with "long time aides and senior White House staff," according to a White House official.

Nearly 2 million have voted in New York City, including early voting.

Totals as of 3:00 p.m.

Manhattan - 453,522

Bronx - 238,730

Brooklyn - 600,187

Queens - 470,251

Staten Island - 144,266

Total 1,906,956

* including early voting check-ins