Cripes! I remember the transition. Democrats relied on the Solid South…racism, Jim Crow laws and all, to stay in power for decades. Then, as a result of pressure from the growing civil rights movement, they relented. They figured they better join the nation changing in a progressive direction.
As a result, the Republican Party took over state government in all the most racist states. That’s what “Republican tradition” means in most of the South. It goes back to the success of freedom fighters at the federal level…and your friendly neighborhood bigots simply changing parties.