The GA Democratic machine stayed with Truman.
But why? The Democratic party machines did not stay with Truman in other Deep Southern states, evidently. So why did Georgia stay loyal?
It's already been said: Richard Russell supported Truman.
^^^^
This.
A number of Southern Democrats (especially Georgia and Texas Democrats) ultimately showed more loyalty to the national party than to the Dixiecratic cause. Kind of similar to what happened in 1928 when Mississippi Governor Theodore Bilbo (a proud racist and strong supporter of segregation), despite the overwhelmingly anti-Catholicism of Mississippi, campaigned for Al Smith in Mississippi by spreading rumors that Hoover danced with black women. The result? A massive landslide in Mississippi while next door Alabama nearly went Republican.
LOL. I was thinking about this at work and was going to site 1928 as an example when I got back home.
Anyway, I spent a little over an hour combing through the internet to see if there was some other reason as to why GA voted for Truman - all I could gather was that Richard Russell, something of a kingpin in Georgia politics, supported Truman (albeit for his own political viability, since he expected Dewey to win.) He was also approached by the States' Rights Democratic Party to be their candidate but refused.
It is important to remember that we do not have the internet as a medium of information, so it all boiled down to who the local Democratic committees, newspapers etc supported. Since I am actually involved in local GOP politics (albeit several decades removed from 1948) I can attest to the local parties' influence.