The 1800 United States presidential election was the fourth quadrennial presidential election. It was held from October 31 to December 3, 1800. In what is sometimes called the "Revolution of 1800", the Democratic-Republican Party candidate, Vice President Thomas Jefferson, defeated the Federalist Party candidate and incumbent, President John Adams. The election was a political realignment that ushered in a generation of Democratic-Republican leadership. This was the first presidential election in American history to be a rematch.

The election of the president and the vice president of the United States is an indirect election in which citizens of the United States who are registered to vote in one of the fifty U.S. states or in Washington, D.C., cast ballots not directly for those offices, but instead for members of the Electoral College. These electors then cast direct votes, known as electoral votes, for president, and for vice president. The candidate who receives an absolute majority of electoral votes is then elected to that office. If no candidate receives an absolute majority of the votes for president, the House of Representatives elects the president; likewise if no one receives an absolute majority of the votes for vice president, then the Senate elects the vice president.