Don't need a seminal research paper to know that.
And they were not "conservative" in any sense except trying to "conserve" slavery. The elite intellectual "progressive" democrats of the time were also the most racist. They were the ones, for instance, that pushed eugenics for blacks (Planned Parenthood), and racial superiority based on scientific data:
https://www.washingtonpost.com/opinions/the-liberals-who-lov...
On the other hand, more Republicans voted for the civil rights act as a percentage than Democrats: https://www.wsj.com/articles/SB1041302509432817073
You're not doing so hot with your example.
Then as now, both parties were big tents and this isn't true, but it is true that the elite intellectual racists were more likely to be Democrats; that weakened in the overlapping pair of political realignments starting with the New Deal, especially the second one triggered by LBJ’s support of the Civil Rights Act.
The first schism between the national Democrats and the racists that went to form the “Dixiecrats” (itself triggered by integration policies supported by national Democrats) fell apart because the Dixiecrats weren't viable as a major party on their own, but the the second schism triggered by LBJ became permanent when the Republicans made attracting the disaffected racists a durable political strategy. That group of proud and open racists migrated from the Democratic Party to the Republican Party between the 1960s and the 1990s, which is why the Confederate-flag waving, openly anti-black, slavery-justifying-and-minimizing, etc., crowd is now consistently behind (or in front leading) the GOP.
Forget it, you're arguing against a bad faith argument.
OP said something along the lines of the "KKK was a conservative groups". GP's response was "ackchully the KKK was Democrats, as if "Democrat" was the opposite of "Conservative".
I also agree that both parties are big tents. But I will continue to argue that the democrats were and are still the more racist party: https://nypost.com/2016/03/21/the-progressive-movements-horr...
"During the heyday of the Progressive movement in the early 20th century, people on the left were in the forefront of those promoting doctrines of innate, genetic inferiority of not only blacks but also of people from Eastern Europe and Southern Europe, as compared to people from Western Europe.
Liberals today tend to either glide over the undeniable racism of Progressive President Woodrow Wilson or else treat it as an anomaly of some sort. But racism on the left at that time was not an anomaly, either for Wilson or for numerous other stalwarts of the Progressive movement."
Your repeated attempts at condescension say much about you and how unfairly you feel life and other people treat you.
Edit: here's a fun college course: https://www.hws.edu/catalogue/pdf/catalogue_16-18.pdf
White Mythologies: Objectivity, Meritocracy, and Other Social Constructions ... Students will explore how systematic logics that position “the West” and “whiteness” as the ideal manifest through such social constructions as objectivity, meritocracy, and race.