Well, Oregon-Washington coast: http://www.recumbentretreat.org/ (The web page isn't updated yet, but we've had our first meetings to organize next year's hootenanny.)
Our annual races have also turned into a recumbent get-together: http://www.ohpv.org/HPC/index.html .

Since the OP is in Nawth Carolina, I wonder if the WHIRL group might have better contacts: http://www.recumbents.com/whirl/ . (I also wonder if WHIRL is still active.)