The Democratic-Republican Party of Jefferson and Madison--pro-slavery politicians--ultimately evolved into today's Democratic Party. The Republican Party came together shortly before the Civil War as a magnet for Abolitionists and the moribund Whig Party. So the Democratic Party tended to be pro-slavery and largely dominated the South before the Civil War. After the emancipation of slaves, it was still largely a pro-segregation, pro-white supremacist party that ultimately backed the Jim Crow laws. In 1915, D.W. Griffith released the cinematic groundbreaker,
Birth of a Nation* (originally
The Klansman), that promoted a white supremacist version of the Civil War that extolled the Ku Klux Klan and vilified former slaves, black elected officials, and so-called "carpetbaggers" from the North. That film was the first film ever to be screened in the White House in 1916 by the southern Democratic President Woodrow Wilson. Until the passage for the 1964 Civil Rights Voting Act, Democrats tended to be a magnet for conservative segregationists, and the South was solidly Democratic. However, the Democratic Party had become dominated by progressives and were largely responsible for the passage of that bill. As predicted by southern Democratic President Lyndon Johnson at the time, the Democratic Party had "lost the South" with its passage. Republicans under Nixon quickly implemented their infamous
Southern Strategy, which took advantage of white segregationist sentiment to flip the South to the Republican Party. So there has been something of a role reversal over time for the two major political parties regarding racial politics. It is now "woke" Democratic policy to remove statues, school names, and other symbols that honor the Confederate side of the Civil War.
*Available on Youtube