List of special elections to the United States Senate

This is an incomplete list of special elections to the United States Senate. Such elections fill the vacancies that occur when a member of the Senate dies or resigns before the biennial general election which precedes the end of his or her six-year term. Winners of these special elections typically serve the remaining two or four years plus two months of that six-year term. General elections to the U.S. Congress are held in November of even-numbered years. New Congresses convened on March 4 of the following year until 1934. Since 1934, new Congresses have begun on January 3 of the following year.

Some states, such as Texas, allow for special elections to the Senate that occur separate from a general election (similar to special elections to the U.S. House), while most wait to hold them in conjunction with the next general election.

Prior to ratification of the Seventeenth Amendment to the United States Constitution, most state legislatures elected U.S. Senators. The Seventeenth Amendment states that special elections will be held to fill vacant Senate seats, but that state legislatures may empower the governor of the state to fill the seat by an appointment between the time that it becomes vacant and the time that the winner of the special election is certified. As of 2009, four states, Massachusetts, Oregon, Wisconsin and Oklahoma require special elections, Oklahoma permitting its governor to appoint only the winner of a special election. Alaska in 2004 enacted legislation and a separate ballot referendum law that took effect on the same day, that conflict. It is uncertain if the Alaska governor may successfully appoint an interim Senator to serve until the mandated special election occurs 60 to 90 days after the vacancy happens. The ballot-approved law fails to specifically authorize the governor to appoint, though the legislative law does.

Since 1913, 184 senators have been appointed to fill vacancies. Of those, 63 did not later run for election; 56 ran and lost the subsequent special election; and 60 ran and won the election.

This list only includes vacancies that were filled by special election. Not included are those situations in which vacancies were only filled by appointment or general election, or new seats.

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