Can someone give a brief description of the democratic "situation" for whites in the Jim Crow South in various times and places?
There's been a lot of plain yes and no answers, but some detailed descriptions would be great. I know very little about the South and would like to know more 
It depends a lot on the state.
In South Carolina for example, the hurdles to voting were so entrenched and steep, that turnout was mostly just limited to the die hard party machine hacks, after all why pay a poll tax and bother with all those tests just to vote in an effectively already decided election? One thing that I remember being mentioned in one of my college classes was that some states actually mandated the poll tax be prepaid, aka it was paid long before election day and if you missed it you couldn't vote that year. And the day it was due was set to coincide right before harvest time when farmers would be lowest on money. So basically all poor farmers of all races were disenfranchised. The election was about as democratic as one to the Soviet Politboro. This was also true in Mississippi and most of Georgia.
But other states were a bit more open or split by region. The Upper South states had Unionist Republican enclaves and while they disenfranchised most blacks, weren't quite as onerous in the limitations. Also true of Alabama to some extent. What those states often did is just threw in loopholes to the restrictions allowing most whites to qualify. For example:
https://en.wikipedia.org/wiki/Disenfranchisement_after_the_Reconstruction_Era#Educational_and_character_requirementsHence why Alabama came close to voting for Hoover in 1928. Compare that to South Carolina, which didn't have a sizable Catholic population obviously.
Meanwhile this is what South Carolina did:
Poll
