The new president can also nominate a vice president of their own choosing, though that nominee must be confirmed by both the House and the Senate.

There are also limits on future elections. If the new president serves less than two years of the original term, they may still run for two full terms of their own. If they serve more than two years, they are eligible for only one additional term.

A modern precedent
The last time this process played out was in 1963, following the assassination of President John F. Kennedy. And that historical example continues to shape today’s procedures for ensuring continuity of government.

Back in 1963, Vice President Lyndon B. Johnson was sworn in as president aboard Air Force One at Dallas Love Field just over two hours after Kennedy’s death.

Johnson chose to retain much of Kennedy’s cabinet, won re-election in 1964, and later opted not to seek another full term.

Eight have died while in office
Out of the 45 men who have served as U.S. President, eight died while still in office—a surprisingly high number for such a position.

Four were assassinated: Abraham Lincoln, James A. Garfield, William McKinley, and John F. Kennedy. William Henry Harrison died of pneumonia in 1841, just a month after taking office, though the popular story that it was caused by skipping a coat at his February inauguration has been debunked.

The other three — Zachary Taylor, Warren G. Harding, and Franklin D. Roosevelt—passed away from various illnesses while serving as president.

What could happen if Trump dies in office
If Donald Trump were to pass away while still in the White House, things could get messy fast.

For one, Trump and his team have a history of ignoring norms, protocols, and even the rule of law, so standard procedures might not go exactly as planned.

A big, extravagant funeral is almost guaranteed, but unlike the outpouring of unity seen after President Kennedy’s death, today’s political climate is far more polarized. With tensions so high and public discourse already deeply divided —much of it shaped by Trump and his supporters — national mourning would likely be anything but universal.