Mexican groups are active in Texas, most notable are Barrio Azteca, Texas Syndicate and Los Zetas. Colombian and Cuban groups are still active in Florida. They aren't as aggressive as they used to be, but they're still around over there and probably won't ever go away.
Down South outlaw motorcycle gangs are deeply rooted. Outlaws MC have their main operations in Florida, Georgia, Indiana, Kentucky, Alabama and Tennessee. Bandidos MC have their roots in Texas, Oklahoma and Mississippi. The so-called 'Dixie mafia' -a term to describe organized crime groups in the South- is probably connected to are even a term for the activities of the OMG's.

But since I'm not from the USA, I can only base this on the reports I've read (which aren't always that trustworthy, even if they're from the FBI). Would be interesting to hear someone from the South on this topic.