The Midwest is like that. In Michigan where the snakes are mostly small kinds, you can find a lot in good habitat, under the right conditions. Last year at this time my friend, Eddie, and I found as many as five ringnecks under one limestone rock, and there's hundreds of rocks on that ridge. We also found a ribbon, E. garters, milks, smooth greens, browns, waters, and an assortment of frogs and toads. We've found massasaugas close by, so are looking for them in this locale too. The whole ridge is surrounded by a swamp.
At home, I like to call Afton Farm (20 acres), we manage the property for the maximum herp habitat. My record is thirteen herps under one rock on a hill (garters, browns, red-bellies, greens, and a skink). Sometimes I'll go out after dinner, at 7:00 at night, and find ten to fifteen snakes in a half hour walk. Once, under a big sign, I found five milksnakes, two of them over four ft. Another time my brother and I found five E. fox snakes and two melanistic garters under one rock (I'll explain that some other time).
You should come out to MI sometime. BTW, I love hunting in N.C. and will be there in August. Later...
TC