Party divisions of United States Congresses have played a central role on the organization and operations of both chambers of the United States Congress—the Senate and the House of Representatives—since its establishment as the bicameral legislature of the Federal government of the United States in 1789. Political parties had not been anticipated when the U.S. Constitution was drafted in 1787, nor did they exist at the time the first Senate elections and House elections occurred in 1788 and 1789. Organized political parties developed in the U.S. in the 1790s, but political factions—from which organized parties evolved—began to appear almost immediately after the 1st Congress convened. Those who supported the Washington administration were referred to as "pro-administration" and would eventually form the Federalist Party, while those in opposition joined the emerging Democratic-Republican Party.
Party divisions by Congress
The following table lists the party divisions for each United States Congress. Note that numbers in boldface denote the majority party at that particular time while italicized numbers signify a Congress in which the majority party changed intra-term.
|Congress||Years||Senate||House of Representatives||President||Trifecta|
|19th||1825–1827||48||26||22||—||—||213||104||109||—||—||John Quincy Adams||No|
|25th||1837–1839||52||35||17||—||—||242||128||100||14||—||Martin Van Buren||Yes|
|29th||1845–1847||58||34||22||—||2||228||142||79||7||—||James K. Polk||Yes|
|41st||1869–1871||74||11||61||—||2||243||73||170||—||—||Ulysses S. Grant||Yes|
|45th||1877–1879||76||36||39||1||—||293||156||137||—||—||Rutherford B. Hayes||No|
|47th||1881–1883||76||37||37||2||—||293||130||152||11||—||Chester A. Arthur||No|
|61st||1909–1911||92||32||59||—||1||391||172||219||—||—||William H. Taft||Yes|
|67th||1921–1923||96||37||59||—||—||435||132||300||1||2||Warren G. Harding||Yes|
|73rd||1933–1935||96||59||36||1||—||435||313||117||5||—||Franklin D. Roosevelt||Yes|
|79th||1945–1947||96||57||38||1||—||435||243||190||2||—||Harry S. Truman||Yes|
|83rd||1953–1955||96||46||48||2||—||435||213||221||1||—||Dwight D. Eisenhower||Yes|
|87th||1961–1963||100||64||36||—||—||437||262||175||—||—||John F. Kennedy||Yes|
|88th||1963–1965||100||67||33||—||—||435||258||176||—||1||Lyndon B. Johnson||Yes|
|101st||1989–1991||100||55||45||—||—||435||260||175||—||—||George H. W. Bush||No|
|107th||2001–2003||100||50||50/49||0/1||—||435||212||221||2||—||George W. Bush||Yes/No|
|Senate||House of Representatives|
Partisan control of Congress
This table shows the number of Congresses in which a party controlled either the House, the Senate, or the presidency.
- U.S. Senate: Party Divisions
- The Anti-Administration Party was not a formal political party but rather a faction opposed to the policies of Treasury Secretary Alexander Hamilton. The faction eventually coalesced into the Democratic-Republican Party.
- The Pro-Administration Party was not a formal political party but rather a faction supportive of the policies of Treasury Secretary Alexander Hamilton. The faction eventually coalesced into the Federalist Party.
- Though Washington never formally joined a party, he was broadly sympathetic to the coalition which later became the Federalist Party.
- Washington disapproved of formal political parties and refused to join either party, though he became a symbol of the Federalist Party.
- The Democratic-Republican Party broke up into two competing parties during the 1820s, but there is no official date of dissolution for the Democratic-Republicans. During the presidency of John Quincy Adams, Congress became divided between a group that favored Adams and a group that favored Andrew Jackson. After Adams left office, Congress was divided into a group that supported the Jackson administration and a group that opposed it. During Jackson's presidency, the pro-Jackson group coalesced into the Democratic Party, while the anti-Jackson group (which included the National Republican Party) joined with the Anti-Masonic Party and other groups to form the Whig Party.
- Adams won election as a Democratic-Republican, but he sought re-election as a National Republican.
- Whig President William Henry Harrison died April 4, 1841, one month into his term, and was succeeded by John Tyler, who served for the remainder of the term. Tyler had been elected as vice president on the Whig ticket, but he became an independent after the Whigs expelled him from the party on September 13, 1841.
- Whigs held their only trifecta from March 4, 1841, until later that year when the Whigs expelled Tyler from the party on September 13 and he became an Independent.
- President Taylor died July 9, 1850, about one year and four months into the term, and was succeeded by Millard Fillmore, who served for the remainder of the term.
- The "Opposition Party" was the congressional coalition formed by former Whigs and members of the nascent Republican Party. The Opposition Party opposed the Democratic Party in the aftermath of the collapse of the Whig Party.
- President Lincoln was assassinated and died April 15, 1865, about a month after beginning his second term as president. He was succeeded by Democrat Andrew Johnson, who served the remainder of the term.
- Johnson was elected as vice president on the National Union ticket, but was a Democrat prior to the 1864 election.
- Republicans had a trifecta until March 4, 1865, when President Lincoln was inaugurated for his second term having run under the National Union Party. Though he was not elected as a Republican, Lincoln practically enabled the Republican Party to have a trifecta until April 15, 1865, when he was assassinated. Once Lincoln's Vice President Andrew Johnson, who was a Democrat prior to the 1864 election, succeeded to the Presidency, Johnson broke the Republican Party's practical trifecta
- Neither party controlled the Senate in the 47th Congress in what's known as the "Great Senate Deadlock of 1881." "The Great Senate Deadlock of 1881". Senate.gov. US Senate. Retrieved 1 July 2014.
- James A. Garfield died September 23, 1881, roughly six months into his term. He was succeeded by Chester Arthur, who served for the remainder of the term.
- McKinley died September 14, 1901, about six months into his second term, and was succeeded by Theodore Roosevelt. Roosevelt served for the remainder of the term and was elected president in 1904.
- The Democratic Party controlled the House in coalition with the Progressive Party and the Socialist Party. The lone congressional member of the Prohibition Party was not a part of this coalition.
- President Harding died August 2, 1923, about two years and five months after becoming president, and was succeeded by vice-president Calvin Coolidge. Coolidge served for the remainder of the term and was subsequently elected president in 1924.
- Roosevelt died April 12, 1945, about three months into his fourth term as president, and was succeeded by Harry S. Truman. Truman served the remainder of the term and was elected president in 1948.
- According to the 20th Amendment to the U.S. Constitution, the new session of Congress begins on the 3rd of January, while the new presidency begins on the 20th of January. For the first seventeen days of this Congress, both the House of Representatives and the Senate were held by Republican Party, while the outgoing President was of the Democratic Party. After these seventeen days, the Republican Party had a trifecta.
- Kennedy died November 22, 1963, about two years and ten months into the term, and was succeeded by Lyndon B. Johnson. Johnson served the remainder of the term and was elected president in 1964.
- According to the 20th Amendment to the U.S. Constitution, the new session of Congress begins on the 3rd of January, while the new presidency begins on the 20th of January. For the first seventeen days of this Congress, both the House of Representatives and the Senate were held by the Democratic Party, while the outgoing President was of the Republican Party. After these seventeen days, the Democratic Party had a trifecta.
- Nixon resigned August 9, 1974, about a year and seven months into his second term as president, and was succeeded by Gerald R. Ford, who served for the remainder of the term.
- According to the 20th Amendment to the U.S. Constitution, the new session of Congress begins on the 3rd of January, while the new presidency begins on the 20th of January. For the first seventeen days of this Congress, the Democratic Party had a trifecta. After these seventeen days, both the House of Representatives and the Senate were held by the Democratic Party, while the President Nixon was of the Republican Party.
- In the 96th, 97th, and 98th Congresses, the only Conservative member of the House, William Carney of New York, caucused with the Republican Party.
- Carney was elected as a Conservative but caucused with Republicans until October 1985, when he joined the Republican Party.
- In the 102nd through 109th Congresses, Independent Bernie Sanders of Vermont's at-large congressional district caucused with the Democratic Party.
- In the 102nd through 109th Congresses, Independent Bernie Sanders of Vermont caucused with the Democratic Party. Independent Jo Ann Emerson switched to the Republican party on January 8, 1997.
- The Democratic Party controlled the Senate in the 107th Congress from January 3 to January 20, 2001 (50-50 tie with Democratic Vice President Al Gore as the deciding vote) and from May 24, 2001, to January 3, 2003 (after Senator Jim Jeffords left the Republican Party to become an Independent and caucus with the Democrats).
- The Republican Party controlled the Senate in the 107th Congress from January 20, 2001 (50-50 tie with Republican Vice President Dick Cheney as the deciding vote) until May 24, 2001, when Senator Jim Jeffords left the Republican Party to become an Independent and caucus with the Democrats.
- In the 107th Congress (after May 24, 2001), and in the 108th Congress and 109th Congress, Independent Jim Jeffords of Vermont caucused with the Democratic Party.
- In the 102nd through 109th Congresses, Independent Bernie Sanders of Vermont caucused with the Democratic Party. Independent Virgil Goode switched to the Republican party on August 1, 2002.
- Republicans only held a trifecta from January 20 until May 24, 2001, when Senator Jim Jeffords left the Republican Party to become an Independent and caucus with the Democrats.
- From the 110th Congress to the 117th Congress, two independent members of the Senate caucused with the Democratic Party, and thus are considered to be a part of the Senate Democratic Caucus. In the 110th, 111th, and 112th Congresses, it was Joseph Lieberman and Bernie Sanders. In the 113th, 114th, 115th, 116th, and 117th Congresses, it was Angus King and Bernie Sanders.
- From January 27 to April 28, 2009, when Senator Arlen Specter (R-Pennsylvania) joined the Democratic caucus, there were 56 Democratic senators, 41 Republicans, two independents, and one undecided seat in Minnesota. That vacancy was filled as an additional Democratic seat on July 7, 2009, with the swearing-in of Al Franken, bringing the totals to 58 Democrats, 40 Republicans, and 2 independents. Seven weeks later, on August 25, Sen. Edward M. Kennedy (D-Mass.) died, lowering the Democratic total to 57 for a month until Paul G. Kirk Jr. (D) was appointed and sworn in as Senator Kennedy's interim replacement on September 25, 2009. Just over four months later, on February 4, 2010, Scott Brown (R) who had won a special election for the seat, succeeded Paul Kirk, returning the Republican caucus to 41, and again reducing the Democratic caucus to 57 plus two independents. [The Democratic caucus dropped again briefly to 56 in the 18 days between the death of Sen. Robert Byrd (D-West Virginia) on June 28, 2010, and the seating of his interim successor, Carte Goodwin (also D) on July 16.] The appointed Democratic senator from Illinois, Roland Burris was succeeded on November 29, 2010, by Mark Kirk, a Republican elected earlier that month, once again dropping the Democratic caucus to 56 with 2 independents facing 42 Republicans for the last month of the 111th Congress. December 2011 Congressional Directory, page 324
- From January 3 to April 28, 2009, prior to Senator Arlen Specter's switch to the Democratic Party, there were 41 Republican senators. The Republican caucus returned to 41 on February 4, 2010, with the swearing in of Scott Brown (R-Mass.) to fill the Democratic seat of Edward Kennedy and Paul Kirk. After Mark Kirk (R-Ill.) replaced Roland Burris as senator from Illinois on November 29, 2010, the Senate in the last month of the 111th Congress stood at 42 Republicans, 56 Democrats, and 2 independents.
- The Democratic Party took control of the Senate in the 117th Congress with the swearing in of Democratic senators Raphael Warnock and Jon Ossoff on January 20, 2021. With the two Independent senators (Bernie Sanders and Angus King) caucusing with the Democrats to create a 50-50 tie, Democratic Vice President Kamala Harris became the deciding vote to give Democrats the majority.
- The Republican Party controlled the Senate in the 117th Congress from January 3 to January 20, 2021.
- In the 117th Congress, Angus King and Bernie Sanders continued to serve as Independent Democrats, and Democratic senator Kyrsten Sinema switched to join them on December 9th, 2022.
- Due to Democrats Jon Ossoff and Raphael Warnock (who defeated Republicans David Perdue and Kelly Loeffler in the Georgia special elections and their runoffs) not being inaugurated until January 20 (the same day which Joe Biden was inaugurated President), the Republicans held the Presidency and the Senate until Biden, Ossoff, and Warnock were all sworn in, at which time the Democratic Party obtained a trifecta.
- Three independent members of the Senate, Angus King, Bernie Sanders, and Kyrsten Sinema, caucused with the Democratic Party, and thus are considered to be a part of the Senate Democratic Caucus.
- The beginning of Lincoln's second term and of George W. Bush's first term began with a trifecta for the Republican Party but ended very shortly after beginning.
- The beginning of William Harrison's term began as a trifecta for the Whigs. It continued after Harrison's death when Tyler became President, but ended shortly after once the Whig Party expelled Tyler into becoming an independent.
- The Democrats and Republicans shared control of the Senate in the 47th United States Congress. In the middle of the 107th United States Congress, control of the Senate switched from the Republican Party to the Democratic Party.
- During the 27th Congress, the Whigs expelled the sitting president, John Tyler, from their party. Tyler governed as an independent.