Boss Hogg wore one. Colonel Sanders wore one. Don Johnson wore one in both Miami Vice and Django Unchained. Though Crockett didn't really embody the typical Southern Gentleman, the white suit (with either a black string tie or white bow tie) has always been used to denote a man of Southern class, gentility, and affluence.
But Why? That's the question, why do Southern men get remembered for wearing white suits?
Looking around the Internet, someone mentioned that a white suit would be cooler and in the south this was important in the southern heat. Yes, white clothing is, indeed, cooler, but not really that cool when you're wearing a shirt, a 3 piece suit and a tie. In addition, the Caribbean is also known for hot weather and their suit of choice is made of Seersucker. (It breathes, you see...) Cuba is also known for white suits, but this doesn't explain how it came to be associated with the affluent Southern Gentleman.
My research found a scan of an old cigar box label which shows an old southern plantation owner in all white thus proving that this is not some TV Trope trotted out for quick character identification. But I was stuck on the why..
Until, that is, I came upon a thread from a few years back where people were talking about the white suit and what it meant and most importantly WHY. You can imagine how hard it is to keep a white suit looking clean and white, especially back in the days of horses and carriages. Not only that, but suits back then were washable as they had no dry cleaning (or worsted wool.) So, it's the simple fact that someone is WEARING a white suit that says it all. It says blatantly, "I have the resources at home to keep the suit looking its best!" This means one must be affluent enough to afford said constant cleaning as well as 2 if not 3 or 4 of these white suits to wear and impress the assembled.
So, if I'm going to be a true southerner, a true Gentleman of the South, I guess I had better get me a white suit. And, a black string tie.
Oh, and fried chicken. Lots of fried chicken.