I am very near the borderline where diamondbacks do not exist. It has always been said that Brier Creek is the line, below which there are diamondbacks, and above which there are not. That is fairly accurate. I've never seen a diamondback here, though I'm only about 5 miles north of Brier Creek. I've seen many south of it, tho'. Strange thing is, I once saw a big diamondback in Allendale County, SC, which is definitely north of Brier Creek. We were deer hunting on horseback on the last day of December when I rode up on him, sunning himself. He went down in a stump hole when he saw me. There was a copperhead lying in the sun right beside him. My buddy went back that afternoon and dug him out, caught him, and carried him to the Columbia, SC Zoo's herpetarium.
I guess they can't read, to know about where they aren't supposed to be.
SRH