The 2024 presidential race will come to an end in a matter of days.

Whatever the outcome, history will be made.

Vice President Kamala Harris would be the first woman to serve as president of the United States.

Donald Trump would be only the second president in history to win another White House term after losing a first attempt at reelection, and will have done so after being the first former president to be convicted of a crime.

"You hear inevitably every four years that this is the most important election of one's lifetime, but there is no question in my mind that this is the most important election of my lifetime, and probably the most important since 1860 when Abraham Lincoln was elected to the presidency and the fate of the country was in the balance," said ABC News presidential historian Mark Updegrove.

Updegrove attributed the historic nature of the race not just to Harris and Trump's backgrounds but, more importantly, to what is at stake for American democracy and diplomacy.

"I've never in my life, again, seen such a marked difference in what the candidates stand for and the policy positions they have articulated," Updegrove said, noting Trump's approach to those issues is a stark departure from any other modern U.S. leader.

It all comes after an unprecedented campaign for both parties.

President Joe Biden announced his reelection bid in April 2023 and easily won every state primary. But a historically-early presidential debate with Trump in late June derailed his campaign after a poor performance stoked Democratic alarm about his age.

Biden dropped out of the race in late July after weeks of pressure from his own party. He immediately endorsed Harris (the first Black and South Asian woman to be vice president) to take his place atop the ticket, and she officially claimed the nomination following an online delegate voting process in early August.

Harris, on stage in Chicago, said they are all in a "fight for America's future" in her acceptance speech.

"It is exceptionally rare for presidential candidates to swap certain roles in the middle of the campaign, period," said Brandon Rottinghaus, a political science professor at the University of Houston. "It was a wild moment for an already crazy cycle."

"Her nomination itself was historic," Rottinghaus added. "If she wins, it will break barriers that the nation has been fighting to break since the 1920s. For a nation that has been more challenged in terms of race relations to nominate and then elect a Black woman is, by any counts, progress."

Harris herself, however, has not made her race or gender a focal point of her campaign.

"That's smart because voters aren't interested in making history so much as being happy with where the country is going, and the voters feel very mixed," said Jim Kessler, the co-founder of the center-left think tank Third Way.

ABC News Chief White House Correspondent Mary Bruce, in the final week of the campaign, asked Harris directly what she thinks about the history she may make.

"I am fully aware of my gender and race," Harris responded. "And I know that it will be very significant in terms of the glass that will be broken. But I do not expect that anyone is going to vote for me because of my gender or race. It has to be because I earn their vote with a plan to make their lives better."

On the other side of the aisle, Trump announced his third bid for the White House way back in November 2022.

Since then, he's faced four criminal indictments -- one of which resulted in a guilty verdict by a jury of his peers in New York for falsifying business records in relation to hush money payments made to an adult film star in the closing days of the 2016 campaign. (Trump has vowed to appeal).

Trump also faced a Republican primary with more than a dozen challengers, including his former vice president, but most dropped out before the Iowa caucus and Trump won all but two state primaries. Trump accepted the GOP nomination in Milwaukee, Wisconsin, just days after he was shot in the ear during an attempted assassination.

"He's a study in resilience and defiance, resurging despite two impeachments, Jan. 6, criminality and consistently flouting democratic norms during his presidency and as a candidate," said Updegrove.

If he were to win, he would be the first former president since Grover Cleveland in 1892 to win a non-consecutive second term.

How will the history books write about the 2024 campaign?

"The Democrats were hungry for a win and despite having an incumbent president who was otherwise performing well needed to energize the ticket dramatically," said Rottinghaus. "On the Republican side, Trump co-opted the Republican Party in a way that made his nomination inevitable. I don't think we ever had a situation like this in the modern era."