We are a "mixed race" society, and always have been. Unfortunately, there have also always been those who see "race" as a distinguishing characteristic of humanity. It is a social construct, usually with an economic/political effect/purpose.
In the past, "racists" were not specifically associated with a particular party or platform. Ironically, that changed with the advent of the Republican party. At that time, Republicans were the champions of racial equality, and Democrats were (generally) the ones resisting that change. That condition prevailed well into the 20th Century - Woodrow Wilson was one of the most overt about it, but there were members on both sides of the aisle that took either view on the issues of race and equality.
It was the advent of the the Civil Rights movement of the 60s that changed the matrix. As a result, the racists were concentrated into one party. By the time Nixon ran, the consolidation was complete. Over the intervening years, we progressed from the soft racism of Reagan (and boy was he bigoted), to the overt racism of Trump, but the underlying policy was the same, as Doug points out.
Trump, though, released the bigotry and made it acceptable, rather than talked about in low voices. Tucker Carlson and Laura Ingraham just blast it out without constraint.
