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National elections take place every even-numbered year. Every four years the president, vice president, one third of the Senate, and the entire House are up for election (on-year elections). On even-numbered years when there isn't a presidential election, one third of the Senate and the whole House are included in the election (off-year elections).


Senate Election Law Guidebook (pdf)

The Guidebook compiles federal and state laws relating to the nomination and election of candidates to the Senate.

Term of a Senator:  When Does It Begin and End? (pdf)

Learn more about the term of a Senator's service.


If a vacancy occurs due to a Senator's death, resignation, or expulsion, the 17th Amendment of the Constitution allows state legislatures to empower the governor to appoint a replacement to complete the term or to hold office until a special election can take place. Typically, a replacement holds office until the next scheduled statewide election.

List of Appointed Senators

History of Elections in the Senate

The Constitution (Article I, section 3) originally  provided for Senators to be chosen by their state legislature. In 1913, after many years of debate, the 17th Amendment to the Constitution was ratified.  It allowed for the direct election of Senators , with the provision that a state’s governor, with a legislative mandate, could appoint a Senator in the event of a vacancy until the next general election (see Appointments, below).

The Decision to Permit State Houses to Elect Senators, June 7, 1787

The Lottery to Choose Senate “Classes,” May 15, 1789

Direct Election of Senators

“Treason of the Senate,” February 17, 1906

Historic Elections

Learn more about some historic elections.

The Senate Elects a Vice President, February 8, 1837

The Florida Case, February 5, 1877

Senator Ousted, July 13, 1912

Key Pittman Barely Elected, January 28, 1913

November 5 Election in Doubt, October 25, 1918

Contested Senate Elections

United States Election, Expulsion, and Censure Cases (book profile)

Related Items

Interested in related materials? Take a look at these Virtual Reference Desk subjects for more information.

Political Parties