No supporting evidence??? That's like saying you don't believe your last Thanksgiving dinner happened because you can't find a study proving it. Exactly what supporting evidence do you need when you've witnessed something yourself??? You know we've all taken history classes and seen the world with our own eyes, right? We all see the world and watch the news don't you? Can you seriously not observe, analyze, think, and reach conclusions with your own brain? Do you have to have a study and someone else to tell you what to think and say? Stop parroting MSNBC or TYT and letting people like Cenk or Maddow do your thinking for you and tell you what to say. Look at history and THINK for yourself, FFS. You don't need a flippin' study to know it's cold outside in January during a snowstorm, do you? "No supporting evidence???" JFC, You've got 170 years of it!
The Dems supported slavery, fought to keep it, created the Ku Klux Klan, implemented and enforced Jim Crow and segregation, fought against the Civil Rights Act, and absolutely positively have treated Blacks like helpless children whose support could be bought.
Instead of defending your party's sordid history of racism, why don't you just say, "Yeah, it's been bad. I hope they do better in the future."