The actual switch that took place happened in the 30's and involved economic theory, not race. From about 1860 until the 30's, republicans believed like the democrats of today, that government needs to be large enough to ensure every citizen has a decent standard of living.  This while the democrats believed in small, limited government and very low taxation and fees. That all changed up to and including the thirties. Democrats changed  to being progressive and believing that the government should be larger and more intrusive to guarantee a decent standard of living while republicans changed to believing that government should become smaller and get out of the way of people trying to earn their own decent standard of living. Democrats used to believe in the individual, republicans the collective. That changed in the 30's to republicans believing in the individual and the democrats believing in the collective. That was the switch between the parties and had nothing to do with race.