How many times has the U.S. Senate been split evenly between Democrats and Republicans?

After the winners of the Georgia U.S. Senate runoffs were sworn in on Jan. 20, the Democratic and Republican caucuses in the U.S. Senate were split 50-50. Vice President Kamala Harris (D) has the tie-breaking vote in the chamber.

This is the fourth time in U.S. history the Senate has been split evenly.

As a result of the general election in 2000, the Senate was split 50-50 for a five-month period. During the final weeks of Bill Clinton’s (D) presidency in 2001, Vice President Al Gore (D) had tie-breaking votes in the Senate, giving Democrats an effective majority. After President George W. Bush (R) and Vice President Dick Cheney (R) were sworn in on Jan. 20, Republicans had an effective majority. That held until June 6, when Sen. Jim Jeffords of Vermont changed his affiliation from Republican to independent and began caucusing with Democrats, giving them the majority.

The Republican and Democratic caucuses were split 48-48 for part of 1954, when Vice President Richard Nixon (R) had the tie-breaking vote. The partisan breakdown of the Senate between 1953 and 1955 changed frequently as nine senators died and one resigned. In July 1953, Republican Sen. Robert Taft (Ohio) died. Democrat Thomas Burke replaced him when the Senate reconvened in 1954. Independent Sen. Wayne Morse (Ore.) caucused with Republicans (until he became a Democrat in 1955), splitting the caucuses 48-48 for a time. The Senate grew to 100 members after Alaska and Hawaii became U.S. states in 1959.

Finally, in 1881, Democrats and Republicans each had 37 seats, in addition to one independent who caucused with Democrats and one who caucused with Republicans. Vice President Chester Arthur (R) had the tie-breaking vote.

Georgia’s 2021 runoff winners, Jon Ossoff (D) and Raphael Warnock (D), were sworn into office on Jan. 20. Harris’ Senate replacement, Alex Padilla (D), was sworn in the same day.

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