Atlanta would be one of the hardest places hit, but it'd undoubtedly rise again. Any Vaults Georgia had would probably be clustered around Atlanta. Hartsfield Jackson and the Terminus for trains in Atlanta would've both been hit as hard as possible. Vault-Tec would probably have predicted this, like everyone else with a brain, so I'm thinking experiments in the vaults would revolve around seeing if Atlanta could rise again after the nukes. The large concentration of GECKs in that small an area would easily revive Atl, I think. The worst that would happen is maybe some of the zoo creatures get mutated. Atlanta would essentially become a southern Valut-City conglomerate, probably erecting walls around the perimeter of the city and connecting all the Vaults in the city, and rebuilding things based off Vault Technology, I feel like by the time the Enclave started poking around, the Atlanta Valut-City conglomerate would be strong enough to prevent an all out Valut 13esque slaughter, so the Enclave would be forced to co-operate with the city. Atlanta would also probably be where the Southern Vault-Tec head quarters is located, and I know it's the birthplace of Nuka-Cola, incorporating all of that, with Enclave protection, Atl Vault-City would be pretty well off.
Atlanta would have risen, but it'd be far from perfect, it'd still be a drop of blue in a sea of red, but that wouldn't stop things from becoming xenophobic and authoritarian, fast. Especially with Enclave assistance. The rest of Georgia would probably devolve pretty quickly into a Confederate state of anarchy, moutainfolk, and rednecks. Florida would be a little split, but the panhandle would certainly come under this "New Confederacy" state of mind. The only other place in Georgia of note might be Athens? I feel like Athens is where non-murderous rednecks and Atlanta rejects would end up, they wouldn't be as technologically advanced or as well defended, but you'd have more freedom than in Atlanta and you wouldn't have to worry as much about being hung or sold into slavery as the rest of the South. Using it's connection to Atlanta, it'd probably establish itself as something of a "Redding" to Atlanta's "Vault-City," it'd be the only other major city in the area, everywhere else in Georgia would be pure red New Confederate territory.
The rest of the south would probably also fall into a similar state of Confederacy based anarchy, exceptions being The Republic of Texas, Southern Louisianna, Florida sans north, and 'maybe' the coasts of North and South Carolina?
Just my theory.
