I think it is more popular in the mid-south (TN, KY, VA, WV, NC) because it seems to grow faster/bigger, most likely because their growing season for it is longer. You don't see any baby ginseng poking up around my area until mid May, sometimes late May. Down in TN a lot are starting to put up berry pods by then. Same thing happens in the fall, I've been out hunting ginseng in mid Sept and only finding stalks, where all the leaves have already fallen off. Down south, sometimes it is mid Oct before the leaves even turn yellow.
The quality of the roots is the same. In my area, the size of the roots are smaller, but again I think that is due to heavier clay soil, and shorter growing season. I've dug plenty of 20+ year roots, that look like a 5 year root from TN.