Well, I can see where indoor plumbing was easier to sell in areas where the temperatures get below zero in the winter....
Really, though, the South post-reconstruction was a disaster. It wouldn't even qualify for third world status. They were chronically mal-nourished which created a situation much like North Korea today. Physical growth and IQ were permanently stunted leading to some stereotypes.
Whites were particularly vulnerable to scurvy and related diseases until they noticed the blacks picking and eating "weeds" from along the riverbanks. That's how Mustard greens and Turnip greens etc. became a Southern staple.
There was a concerted effort starting with Wilson and continuing through Roosevelt to rebuild the South economically. That reinforced the South as a Democratic stronghold.
In 1936 South Carolina voted 98.57% for Roosevelt. In the whole state there were only 1650 votes for Landon. The next year there were 1650 lynchings.
The South will be back solidly Democratic before we hit the quarter century mark.