Who were the few R voters in the Deep South until 1944?

[Indy Texas]

New Orleans always had a fairly decent community of non-Southerners who had moved there to work in the shipping industry. You also had the United Fruit Company (which basically fulfilled every top-hatted, mustache-twirling stereotype ever conceived about sinister businessmen) headquartered there, but it was mostly funded and ran by Northern financiers.

I'd assume there were a very small handful of blacks who managed to fit through the various Jim Crow hurdles of literacy tests and property requirements and the like. But by and large, it was probably people who were not from the South but had moved there for work. For that reason, they were probably higher income than average and probably had higher education levels. (Poor people generally have little reason to move for work since they tend to be in relatively interchangeable jobs that can be found anywhere, and back then could also have been substistance farmers.)

[Indy Texas]

Well, there were notable concentrations of racially moderate whites in New Orleans and Atlanta, even back then.  I believe that fairly significant black voting continued in Atlanta during that time as well.  That could be enough to explain Louisiana and Georgia being over 10%. 

Overall, this is ambiguous because some of the Republican candidates during that time were decidedly populist-Progressive and others were decidedly conservative.  Alabama in 1920 is particularly interesting because Harding was known as one of the most racially open presidents during that time period.  There must have been a strong anti-Progressive faction in Alabama then.

Also, AL and MS seem to often be lumped together, but it appears that Alabama was much more Republican relatively, especially in 1900-1928.  MS and SC seem to be inconceivably monolithic.

North Alabama is where the Appalachians begin - it was never part of the lowland plantation economy. I've driven through northern Alabama and was taken aback by the forests and the hills and valleys - all that seemed to be missing was a few log cabins and some people in pioneer clothes. Mississippi, on the other hand, was pretty much one giant cotton plantation.