The States' Rights Democratic Party (whose members are often called the Dixiecrats), also colloquially referred to as the Dixiecrat Party, was a short-lived segregationist, States' Rights, and old southern democratic political party in the United States, active primarily in the South.

It arose due to a Southern regional split in opposition to the national Democratic Party. After President Harry S. Truman, the leader of the Democratic Party, ordered integration of the military in 1948 and other actions to address civil rights of African Americans, including the first presidential proposal for comprehensive civil and voting rights, many Southern white politicians who objected to this course organized themselves as a breakaway faction. They wished to protect the ability of states to decide on racial segregation. Its members were referred to as "Dixiecrats", a portmanteau of "Dixie", referring to the Southern United States, and "Democrat".

In the 1930s, a political realignment occurred largely due to the New Deal policies of President Franklin D. Roosevelt. While many Democrats in the South supported substantive economic intervention, civil rights for African Americans were not specifically incorporated within the New Deal agenda, due in part to Southern control over many key positions of power within the U.S. Congress. Supporters assumed control of the state Democratic parties in part or in full in several Southern states. They opposed racial integration and wanted to retain Jim Crow laws and other aspects of de jure and de facto racial discrimination. On non-racial issues, they held heterogeneous beliefs. Despite the Dixiecrats' success in several states, Truman was narrowly re-elected. After the 1948 election, its leaders generally returned to the Democratic Party, at least for a time, although the Dixiecrats weakened Democratic identity among white Southerners. The Dixiecrats' standard bearer, Senator Strom Thurmond of South Carolina, eventually switched to the Republican Party in 1964, in opposition to national civil rights legislation.

Since the beginning of Reconstruction, Southern white voters supported the Democratic Party by overwhelming margins in both local and national elections, (the few exceptions include minor pockets of Republican electoral strength in Appalachia, East Tennessee in particular, Gillespie and Kendall Counties of central Texas) forming what was known as the "Solid South". Even during the last years of Reconstruction, Democrats used paramilitary insurgents and other activists to disrupt and intimidate Republican freedman voters, including fraud at the polls and attacks on their leaders. The electoral violence culminated in the Democrats regaining control of the state legislatures and passing new constitutions and laws from 1890 to 1908 to disenfranchise most blacks and many poor whites. They also imposed Jim Crow, a combination of legal and informal segregation acts that made blacks second-class citizens, confirming their lack of political power through most of the southern United States. The social and economic systems of the Solid South were based on this structure, although the white Democrats retained all the Congressional seats apportioned for the total population of their states. Three-time Democratic Party presidential candidate William Jennings Bryan opposed a highly controversial resolution at the 1924 Democratic National Convention condemning the Ku Klux Klan, expecting the organization would soon fold. Bryan disliked the Klan but never publicly attacked it.

In the 1930s, a political realignment occurred largely due to the New Deal policies of President Franklin D. Roosevelt. While many Democrats in the South had shifted toward favoring economic intervention, civil rights for African Americans was not specifically incorporated within the New Deal agenda, due in part to Southern control over many key positions of power within the U.S. Congress. Nonetheless, civil rights gained an outspoken champion in First Lady Eleanor Roosevelt, and supportive approaches from the administration's "Black Cabinet".

With the entry of the United States into the Second World War, Jim Crow was indirectly challenged. More than one and a half million black Americans served in the U.S. military during World War II, where they received equal pay while serving within segregated units. (While equally entitled to receive veterans' benefits after the war, the vast majority of African American veterans were prevented from accessing most benefits due in part to Southern success in Congress to have benefits administered by the states instead of the federal government.) Tens of thousands of black civilians at home were recruited in the labor-starved war industries across many urban centers in the country, mainly due to the promotion of Executive Order 8802, which required defense industries not to discriminate based on ethnicity or race.

Members of the Republican Party (which nominated Governor of New York Thomas E. Dewey in 1944 and 1948), along with many Democrats from the northern and western states, supported civil rights legislation that the Deep South Democrats in Congress almost unanimously opposed. Southern Democratic ideology on non-racial issues was heterogeneous. Some such as Fielding L. Wright supported the tenets of the New Deal, others such as Harry F. Byrd joined the conservative coalition. The Dixiecrats' presidential candidate, Strom Thurmond, became a Republican in 1964, as the Republican standard bearer opposed civil rights laws. The Dixiecrats represented the weakening of the "Solid South". (This referred to the Southern Democratic Party's control of presidential elections in the South and most seats in Congress, partly through decades of disfranchisement of blacks entrenched by Southern state legislatures between 1890 and 1908.) The Republicans of the lily-white movement in the South also turned against blacks. Blacks had formerly been aligned with the Republican Party before being excluded from politics in the region, but during the Great Migration African Americans had found the Democratic Party in the North, West and the national Democratic party more suited to their interests.

After Roosevelt died, the new president Harry S. Truman established a highly visible President's Committee on Civil Rights and issued Executive Order 9981 to end discrimination in the military in 1948. A group of Southern governors, including Strom Thurmond of South Carolina and Fielding L. Wright of Mississippi, met to consider the place of Southerners within the Democratic Party. After a tense meeting with Democratic National Committee (DNC) chairman and Truman confidant J. Howard McGrath, the Southern governors agreed to convene their own convention in Birmingham, Alabama if Truman and civil rights supporters emerged victorious at the 1948 Democratic National Convention. In July, the convention nominated Truman to run for a full term and adopted a plank proposed by Northern liberals led by Hubert Humphrey calling for civil rights; 35 Southern delegates walked out. The move was on to remove Truman's name from the ballot in the southern United States. This political maneuvering required the organization of a new and distinct political party, which the Southern defectors from the Democratic Party chose to brand as the States' Rights Democratic Party.