If Mr. Booke based the accent on Strom Thurmond it was not Georgia or South Alabama, Strom came from Edgefield, South Carolina. I am 68 and was born and raised here so I can attest that there used to be many, many different accents in this state. In fact it was forty years ago that I took a job based here where I am now, just fifty miles from the little farm where I grew up and when I first came here every time I opened my mouth someone would comment that I was obviously, “not from this part of the state.”
Fifty years ago a man from Orangeburg and a man from Spartanburg might have had a difficult time understanding each other. I can drive from the high school I attended to Lake City, SC in about two hours maximum but in 1960 a young teacher who grew up on a tobacco farm near Lake City and had just graduated from Clemson came to our school to teach vocational agriculture and we were amazed how different his accent was from ours. He told us that, “Peepal frum da lowa pot de ste-at tawk different.” Some of us used to read the State Newspaper which was published in Columbia but people in some parts of the state read, “Da Ste-at Peppa”.
I actually preferred it that way, now everyone is beginning to sound a lot more alike, I have a nephew age 26 who grew up at Fort Mill, SC which is close to Charlotte, NC, he sounds like a radio announcer in comparison to what I grew up hearing. I would like to hear just once more, “You set yoseff down rye cheer in da rockin’ cher an’ make yoseff at home.” I miss Ol’ Strohm and the way he used to say “hoose” instead of house.
I think that reflects the various origins of Carolinian demography, the semipermanent division between Tidewater country and the piedmont (which also obtains in North Carolina and Virginia), and what philologists would call linguistic drift, the tendency of shared languages to differentiate among communities. A good example of the latter would be England itself: in addition to Standard English (pronounced among the middle class in the way familiar from listening to a long line of BBC announcers), England also had -- still has -- its dialects in Derbyshire and Yorkshire that were based directly on Middle English and are incomprehensible today to anyone not schooled in "Yorkshire dialect". These are true dialects (in America, we tend to overwork the word, applying it to accents as well as truly dialectal speechways like Gullah).
In the 19th century there were also numerous local accents in England (like the Somerset "dialect", in which the "s" is sounded like "z", so that the people there say they come from "Zummerzet"), but these were enthusiastically suppressed by ridicule and withdrawal of society by the upper classes through the public schools and social intimidation. In an episode of Are You Being Served?, the '70's BBC comedy series, the actors are put in a (ridiculous) situation in which they must try to pass themselves off as certain upper-class persons. Part of the ruse requires them to ape the accents of the persons they are impersonating, in the course of which one of the actors displays his mastery of various speechways: he is told that his mark comes from Somerset (impersonation of Somerset accent) .... and attended Eton (impersonation of Etonian with the remains of a Somerset accent). It was a comic-phonological tour de force.
In the 18th century, the situation was so fragmented that Dr. Johnson was moved to write his dictionary, for the guidance of even gentle folk who were penning diary entries like, "A mollinkolloi accidence is happent at the house", and Noah Webster, observing similarly motley speechways during the mustering-out and disbandment of George Washington's Continental Army (the Maine men spoke only French, and the Germans from Pennsylvania had been accustomed, at home, to open fire immediately in the direction of anyone they heard speaking English out in the woods, on the reasonable assumption that it was the damned Scots-Irish out stealing again), sat down and wrote his famous dictionary for the guidance of his new countrymen.
H.L. Mencken was interested by "dialectal" differentiation all his life, and wrote The American Language in three weighty volumes to describe it all. He was both a scholar and a patriot -- as well as a public curmudgeon.
Carolina had an original social differentiation between the Tidewater planters, who originally came from the British Caribbean (the lesser Antilles and Jamaica) and brought the plantation system with them, and the Jeffersonian yeomen of the Piedmont above the Fall Line, who were freeholders from all over England, Scotland, and Germany (the Georges were originally Electors of Hanover, German princes, and continued to have substantial German holdings even in the time of George IV: Nassauers were prominent in the British ranks at Waterloo).
It was a feature of early Carolina politics that the Tidewater planters aligned their (moneyed) interests with the Federalists, and their disproportionate representation in the legislature -- it was a stranglehold -- gave them the ability to ratify the Constitution despite its rejection by the majority of South Carolinians, whereas the yeomanry were Antifederalists and loathed moneyed wheeler-dealers (he founded the Bank of New York) like Alexander Hamilton. Rightly so, since it was Hamilton's successors who burned out South Carolina in 1865, just to make a point about who was in charge.
So the difference in accents you noticed represent today the original differences in populations in Federal Period Carolina.
The "radio announcer" accent is what Mencken called the General American accent, which is a Midwestern accent now being propagated by radio and TV. Illinoisans exemplify it best, followed by people from Indiana, Ohio, Iowa (but not Minnesota! -- as with Sarah Palin), and California. At a firm where I worked, my division manager was from southern Illinois, and one of the engineers was a Californian: they had almost identical accents and sounded like actor James Garner (The Rockford Files, Maverick, The Notebook, Space Cowboys). My own was Indiana underneath a lot of Texas, Louisiana, and Georgia, and people have told me all my life that, just like your nephew, I sound like a radio announcer, and have I ever considered, etc.
I heard Strom Thurmond speak at my high school in 1964, in opposition to Communism.
The south Alabama/western Florida accent and the New Orleanian "silk stocking" (Garden District) accent are all descended from South Carolinian planters who moved west. Their accent is English in origin. That of northern Alabama, Mississippi, Arkansas, Kentucky, and the Piedmont is Scots-Irish.
Georgians are a separate case and have a distinctive accent, since Georgia was settled (except for north Georgia, which was settled by Scots-Irish) in the 1730's - 1770's by Englishmen who came directly from England in many cases, with a few Carolinians and German-speaking Salzburger and Moravian religious sectaries thrown in. Whereas the Tidewater Carolinian accent was that of Englishmen who'd spent generations in the Caribbean before coming to North America 90 years before any Georgia settlers showed up.