To win in a Southern state around that era, Democrats needed two things:
1-A solid reliable core of Democratic votes in a large urban center that weren't nullified by suburban Republicans.
2-Still strong support from Dixiecrats in rural areas.
3. Georgia also has something other Southern states don't, which is a fairly large black upper-middle/professional class in Atlanta that is able to be more politically engaged.
That may also tie back to the fact that the relationship between the Georgia Democratic Party and the business community was cordial and thus Republicans may have found it harder to tap into them as a source of campaign contributions.
4. Georgia's Republican Party often ran fairly moderate (for the GOP) candidates for statewide office. When you combine that with the relatively conservative bent of the Democratic candidates for statewide office, this may have unintentionally delayed the migration of conservative whites into the GOP for downballot races. The GOP candidates also often tried to woo Atlanta-area black voters to their side, which may have hurt them with whites more than it helped them with blacks.
