First lady Melania Trump will vote in Palm Beach Tuesday morning, according to her chief of staff and spokeswoman, Stephanie Grisham.

The president cast his ballot last month in person in Palm Beach County.

-ABC News' Ben Gittleson

Biden held his first of two rallies in Pittsburgh, delivering an altered version of his stump speech that focused more forcefully on his pitch to the African American community, and criticism of the president’s treatment of the group.

He expanded his pitch to Black and brown voters, talking about the importance of Black businesses to systemic racism and Trump’s claim that he has been the best president for Black America since Abraham Lincoln.

“Honk if you think his commitment of having done more for the African American community that  Abraham Lincoln is true? Honk your horn,” Biden said and getting silence in return.

“You got it, man, Pittsburgh. Honk if you think it's a bunch of malarkey,” he said and was answered with a chorus of honks.

Biden’s pitch to black voters is one of his lengthier set of remarks about African American issues.

In Miami, former President Barack Obama made another impassioned plea for Americans to head to the polls and made another stinging indictment of Trump's four years in office.

“After four years of failure and division, we have the power to change America. Tomorrow, you can put an end to the politics that tries to pull us apart, just to win the election," he said.

"Florida, you delivered for me twice. And now I'm asking you to deliver for all of us, and elect Joe Biden and Kamala Harris as the next president and vice president of the United States of America,” he added.

-ABC News' Molly Nagle and John Verhovek

There's a good chance we won't know who won the presidential election on election night.

More people than ever are voting by mail this year due to the pandemic, and mail ballots take longer to count than ballots cast at polling places. But because each state has its own rules for how votes are counted and reported, some will report results sooner than others.

Those disparate rules may also make initial returns misleading: The margins in some states may shift toward Democrats as mail ballots -- which are overwhelmingly cast by Democrats -- are counted, while states that release mail ballots first may experience a shift toward Republicans as Election Day votes are tallied.

FiveThirtyEight compiled a complete guide to poll closing times, vote counting and races to watch on election night.

-FiveThirtyEight's Nathaniel Rakich and Elena Mejia

Biden and Lady Gaga, who is performing tonight at his drive-in rally in Pittsburgh, visited the University of Pittsburgh to greet supporters and student organizers.

They each thanked the volunteers for their hard work, with Biden adding his praise for the young supporters.

"Thank you, thank you, thank you for all you're doing for us. By the way, you are the most incredible generation there is. For real. Z Generation and all -- all kidding aside, you're the best educated, you're the brightest, you're the least prejudiced, you're the most engaged and most open generation in American history. That's why we're counting on you," Biden said.

The Democratic nominee also joked about their joint event later, telling volunteers, "Lady Gaga's gonna be speaking and I'm gonna be singing."

-ABC News' Molly Nagle