Lets see when did the Republican party get it's start? With Lincoln? Since lincoln was a profound racist, one must conclude that Republican were racist from the very beginning!
"I will say, then, that I am not, nor ever have been, in favor of bringing about in any way the social and political equality of the white and black races--that I am not nor ever have been in favor of making voters or jurors of negroes, nor of qualifying them to hold office, nor to intermarry with white people; and I will say in addition to this that there is a physical difference between the white and black races which will ever forbid the two races living together in terms of social and political equality. And inasmuch as they cannot so live, while they do remain together, there must be the position of superior and inferior. I am as much as any other man in favor of having the superior position assigned to the white race."
Abe Lincoln
Abraham Lincoln: Dark Side of a Liberaor
The real question is when did the Democrats stop being a mostly racist party.....