The 1996 United States Senate elections were held on November 5, 1996, with the 33 seats of Class 2 contested in regular elections. Special elections were also held to fill vacancies. They coincided with the presidential election of the same year, in which Democrat Bill Clinton was re-elected president.
The 1990 United States Senate elections were held on Tuesday, November 6, 1990, with the 33 seats of Class 2 contested in regular elections. Special elections were also held to fill vacancies. The Democratic Party increased its majority with a net gain of one seat from the Republican Party. The election cycle took place in the middle of President George H. W. Bush's term, and as with most other midterm elections, the party not holding the presidency gained seats in Congress. This was the first time since 1980 that any party successfully defended all their own seats, and the first time Democrats did so since 1958.
The 1986 United States Senate elections were elections for the United States Senate. Held on November 4, in the middle of Ronald Reagan's second presidential term, the 34 seats of Class 3 were contested in regular elections. The Republicans had to defend an unusually large number of freshman Senate incumbents who had been elected on President Ronald Reagan's coattails in 1980. Democrats won a net of eight seats, defeating seven freshman incumbents, picking up two Republican-held open seats, and regaining control of the Senate for the first time since January 1981. This remains the most recent midterm election cycle in which the sitting president's party suffered net losses while still flipping a Senate seat.
The 1984 United States Senate elections were held on November 6, with the 33 seats of Class 2 contested in regular elections. They coincided with the landslide re-election of President Ronald Reagan in the presidential election. In spite of the lopsided presidential race, Reagan's Republican Party suffered a net loss of two Senate seats to the Democrats, although it retained control of the Senate with a reduced 53–47 majority.
The 1980 United States Senate elections were held on November 4, coinciding with Ronald Reagan's victory in the presidential election. The 34 Senate seats of Class 3 were contested in regular elections. Reagan's large margin of victory over incumbent Jimmy Carter gave a huge boost to Republican Senate candidates, allowing them to flip 12 Democratic seats and win control of the chamber for the first time since the end of the 83rd Congress in January 1955. This was the first time since 1966 that any party successfully defended all their own seats.
The 1978 United States Senate elections were held on November 7, in the middle of Democratic President Jimmy Carter's term. The 33 seats of Class 2 were contested in regular elections. Special elections were also held to fill vacancies.
The 1974 United States Senate elections were held on November 5, with the 34 seats of Class 3 contested in regular elections. They occurred in the wake of the Watergate scandal, Richard M. Nixon's resignation from the presidency, and Gerald Ford's subsequent pardon of Nixon. Economic issues, specifically inflation and stagnation, were also a factor that contributed to Republican losses. As an immediate result of the November 1974 elections, Democrats made a net gain of three seats from the Republicans, as they defeated Republican incumbents in Colorado and Kentucky and picked up open seats in Florida and Vermont, while Republicans won the open seat in Nevada. Following the elections, at the beginning of the 94th U.S. Congress, the Democratic caucus controlled 60 seats, and the Republican caucus controlled 38 seats.
The 1972 United States Senate elections were held on November 7, with the 33 seats of Class 2 contested in regular elections. They coincided with the landslide re-election of Republican President Richard Nixon. Despite Nixon's landslide victory, Democrats increased their majority by two seats. The Democrats picked up open seats in Kentucky and South Dakota, and defeated four incumbent senators: Gordon Allott of Colorado, J. Caleb Boggs of Delaware, Jack Miller of Iowa, and Margaret Chase Smith of Maine. The Republicans picked up open seats in New Mexico, North Carolina, and Oklahoma, and defeated one incumbent, William B. Spong Jr. of Virginia.
The 1970 United States Senate elections was an election for the United States Senate. It took place on November 3, with the 33 seats of Class 1 contested in regular elections. Special elections were also held to fill vacancies. These races occurred in the middle of Richard Nixon's first term as president. The Democrats lost a net of three seats, while the Republicans and the Conservative Party of New York picked up one net seat each, and former Democrat Harry F. Byrd Jr. was re-elected as an independent.
The 1968 United States Senate elections were elections for the United States Senate. Held on November 5, the 34 seats of Class 3 were contested in regular elections. They coincided with the presidential election of the same year. The Republicans picked up five net seats in the Senate. This saw Republicans win a Senate seat in Florida for the first time since Reconstruction.
The 1966 United States Senate elections were elections on November 8, 1966, for the United States Senate which occurred midway through the second term of President Lyndon B. Johnson. The 33 seats of Class 2 were contested in regular elections. Special elections were also held to fill vacancies. With divisions in the Democratic base over the Vietnam War, and with the traditional mid-term advantage of the party not holding the presidency, the Republicans took three Democratic seats, thereby breaking Democrats' 2/3rds supermajority. Despite Republican gains, the balance remained overwhelmingly in favor of the Democrats, who retained a 64–36 majority. Democrats were further reduced to 63–37, following the death of Robert F. Kennedy in June 1968.
The 1964 United States Senate elections were held on November 3. The 33 seats of Class 1 were contested in regular elections. Special elections were also held to fill vacancies. They coincided with the election of President Lyndon B. Johnson by an overwhelming majority, to a full term. His Democratic Party picked up a net two seats from the Republicans. As of 2023, this was the last time either party has had a two-thirds majority in the Senate, which allowed the Senate Democrats to override a veto, propose constitutional amendments, or convict and expel certain officials without any votes from Senate Republicans. However, internal divisions would have prevented the Democrats from having done so. The Senate election cycle coincided with Democratic gains in the House in the same year.
The 1962 United States Senate elections was an election for the United States Senate. Held on November 6, the 34 seats of Class 3 were contested in regular elections. Special elections were also held to fill vacancies. They occurred in the middle of President John F. Kennedy's term. His Democratic Party made a net gain of four seats from the Republicans, increasing their control of the Senate to 68–32. However, this was reduced to 67–33 between the election and the next Congress, as on November 18, 1962, Democrat Dennis Chávez, who was not up for election that year, died. He was replaced on November 30, 1962, by Republican appointee Edwin L. Mechem. Additionally, Democrat Strom Thurmond became a Republican in 1964, further reducing Democrats to 66–34. This was the first time since 1932 that Democrats gained seats in this class of Senators.
The 1958 United States Senate elections were elections for the United States Senate which occurred in the middle of President Dwight D. Eisenhower's second term. Thirty-two seats of Class 1 were contested in regular elections, the new state of Alaska held its first Senate elections for its Class 2 and 3 seats, and two special elections were held to fill vacancies.
The 1956 United States Senate elections were elections for the United States Senate that coincided with the re-election of President Dwight D. Eisenhower. The 32 seats of Class 3 were contested in regular elections, and three special elections were held to fill vacancies. Although Democrats gained two seats in regular elections, the Republicans gained two seats in special elections, leaving the party balance of the chamber unchanged.
The 1952 United States Senate elections was an election for the United States Senate which coincided with the election of Dwight D. Eisenhower to the presidency by a large margin. The 32 Senate seats of Class 1 were contested in regular elections, and three special elections were held to fill vacancies. The Republicans took control of the Senate by managing to make a net gain of two seats. However, Wayne Morse (R-OR) became an independent forcing Republicans to rely on Vice President Richard Nixon's tie-breaking vote, although Republicans maintained a 48–47–1 plurality. Wayne Morse would caucus with the Republicans at the start of Congress’ second session on January 6, 1954 to allow the GOP to remain in control of the Senate. This was the third time, as well as second consecutive, in which a sitting Senate leader lost his seat.
The 1938 United States Senate elections occurred in the middle of Franklin D. Roosevelt's second term. The 32 seats of Class 3 were contested in regular elections, and special elections were held to fill vacancies. The Republicans gained eight seats from the Democrats, though this occurred after multiple Democratic gains since the 1932 election, leading to the Democrats retaining a commanding lead over the Republicans with more than two-thirds of the legislative chamber.
The 1932 United States Senate elections coincided with Democrat Franklin D. Roosevelt's landslide victory over incumbent Herbert Hoover in the presidential election. The 32 seats of Class 3 were contested in regular elections, and special elections were held to fill vacancies.
The 1930 United States Senate elections occurred in the middle of Republican President Herbert Hoover's term. The 32 seats of Class 2 were contested in regular elections, and special elections were held to fill vacancies. With the Great Depression beginning to take hold, Republican incumbents became unpopular, and Democrats picked up a net of eight seats, erasing the Republican gains from the previous election cycle, however, Republicans retained control of the chamber. This was the first of four consecutive Senate elections during the Depression in which Democrats made enormous gains, achieving a cumulative pick-up of 34 seats.
The 1954 South Carolina United States Senate election was held on November 2, 1954. Senator Burnet R. Maybank did not face a primary challenge in the summer and was therefore renominated as the Democratic nominee for the election in the fall. However, his death on September 1 left the Democratic Party without a nominee, and the executive committee nominated state Senator Edgar A. Brown as their replacement candidate. Many South Carolinians were outraged by the party's decision to forgo a primary election, and former Governor Strom Thurmond entered the race as a write-in candidate. He easily won the election and became the first U.S. senator to be elected by a write-in vote in an election where other candidates had ballot access. A Senate election where the victor won by a write-in campaign did not happen again until 2010.
