I think something to realize here is that political parties aren't racist by definition. Racism is strictly personal. Sure you have the KKK and neo-nazi groups, but they formed by racism. Neither the Democratic or Republican parties were formed by racism, although throughout history racists have backed either party. Currently, the outspoken white racists are a majority of conservative/republicans. That doesn't mean anything for the republican party at all... at the same point, the racists back in the day you may be referring to had racist support quite possibly, but the political party had nothing to do with systematic racism.
America has an extreme racist history. They wiped out generations of native americans, tragic. Up until very recently black people had less rights than animals. So yeah, it's easy for you to paint a picture of a racist democratic party, but it means nothing in the grand scheme of things, just like the racists that vote for republicans don't mean shit either.