The 1800–01 United States Senate elections were held on various dates in various states, coinciding with Thomas Jefferson being elected to the White House. As these U.S. Senate elections were prior to the ratification of the Seventeenth Amendment in 1913, senators were chosen by state legislatures. Senators were elected over a wide range of time throughout 1800 and 1801, and a seat may have been filled months late or remained vacant due to legislative deadlock. In these elections, terms were up for the senators in Class 3.

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.