We're obviously going to hear about a lot of different issues tonight — and some of those issues will be comfortable ground for Trump, while others will be Harris' home turf. The latest ABC News/Ipsos poll asked Americans whether they trusted Trump or Harris more to handle 11 different issues. Harris was trusted more on six, Trump was trusted more on four, and one (crime and safety) was tied.

Harris also had the biggest trust advantage on any issue: 16 points, on both abortion and race relations. However, Trump was trusted more than Harris on the three issues that Americans usually say are the most important to their vote: the economy, inflation and immigration.

—538's Nathaniel Rakich

Members of the Trump family attending the debate with him tonight are his son Eric Trump and his son's wife -- and co-chair of the Republican National Committee -- Lara Trump, sources familiar with the matter tell ABC News.

On the plane with him from Florida to Philadelphia were Florida Rep. Matt Gaetz and former Democratic Rep. Tulsi Gabbard, who have been helping Trump with debate prep. Also on board -- one of his lawyers, Alina Habba, as well as senior staffers Chris LaCivita, Susie Wiles, Steven Cheung, Corey Lewandowski and Jason Miller.

Notably, controversial conservative media influencer Laura Loomer was also flying with Trump. Loomer has pushed multiple conspiracy theories about Harris, including racist and sexist attacks on the vice president.

-ABC News' Lalee Ibssa and Katherine Faulders

Trump landed at Philadelphia International Airport a short while ago for the debate. He could be seen raising his fist as he departed his plane.

It's a hallmark of the American electoral process: the presidential debate.

The first nationally televised debate in history featured John Kennedy and Richard Nixon. The visuals did not play in Nixon's favor, as he was seen sweating and looking pale after previously being hospitalized for an infection, while Kennedy looked young and gave a more vigorous performance.

More than 20 years later, Ronald Reagan, the oldest sitting president at the time, shut down some questions about his age during his debate with Democrat Walter Mondale.

In 1992's trilateral debate, President George H.W. Bush was criticized for looking down at his watch. In 2000, Al Gore was mocked for his audible sighs during his debate with George W. Bush.

In the 2020 Democratic primary, one highlight was Harris' challenge to Joe Biden on the issue of segregation and busing, which prompted her viral quote, "That little girl was me."

Most recently, the debate between President Biden and Trump changed the course of the 2024 campaign after Biden's poor performance exacerbated Democratic and voter concerns about his age and fitness to serve another four years. He announced he was exiting the race 24 days later.