But there certainly is a lot of overlap between Slave Owning and Republican States.

Only in the last forty years. These used to be staunchly Dixiecrat territories prior to the Southern Strategy.

But I might point you to a different map.

A huge part of the D/R switch under Nixon/Reagan came through Gulf Coast O&G tycoons. That's what gets us Wyoming and W. Virginia as bright red. It's why Pennsylvania - home of the Gettysburg address along with some of the fiercest abolitionist activists and civil rights organizations - into the purple category.

The degree to which the country has become a Petro-State has revolutionized politics domestically.

So long as that industry endures, the GOP-aligned land barons are going to have all the money they need for revanchist political projects.