Here's a link to the
National Feral Swine Mapping System maintained by USDA. It should give you a good idea where hogs are. You can only go so far down as a public user, but if you need more specific info for any place, just ask and I can get it for you. Of course, its not perfect - its only as good as the info plugged in ie: see western Oklahoma, and the sudden stop of pigs at the northern california border - but it should give you a good idea.
I would check any area that has a good number of domestic hog farming. They always manage to lose hogs, these become feral. I would imagine that there are some areas in a neighboring state that has some industrial hog farming. I'd look into those.
Feral Hogs aren't the result of escaped pigs from modern hog farms. Those pigs don't/cant escape. And as we've seen with trucks in accidents, they tend to not travel far from the accident because they have no idea what to do in the wild. They are pretty domesticated and don't want to run away. Plus, the males are all castrated.
Feral hogs come from people who have released them. They also happen naturally by migration of existing pigs. Also, the original pigs in this country were released into the wild by the Spanish who hunted them down. Game farms are also a big source of feral pigs. And so called "organic" and pasture swine operations have some problem with it, but not industrial farms. Older style farms - the kind that largely went out of style in the early 90s, had some problems with escapees - but those kind of farms really don't exist in any great numbers anymore.
As Hogdogs says, a lot of the problem happened when the industry totally collapsed in the 80s. Especially in Georgia and Florida.
The pig business, if you can believe it, is actually in the middle of an even more severe economic crisis currently than it was in the 80s. This one though isn't caused by market dynamics and the emergence of more efficient competitor farms - its 100% the result of the tremendous federal subsidies and tax incentives for turning corn into ethanol.