Luckily they're very shy, so you don't see them very often and they have small mouths so they have to get hold of something like your toes or fingers in order to envenomate.
@Sanguine They are supposed to exist at least as far north as Virginia,but I grew up in Virginia and spent a lot of time wandering around in the woods,and never saw one.
BTW,I have always heard black snakes being called King Snakes because they are so big and long they wrap around smaller snakes and just stretch and pull them apart. Once saw a big black snake and a big cottonmouth wrestling across my yard and raising up a cloud of dust at the black snake was trying to wrap around the cottonmouth,and the cottonmouth was trying to avoid it. They eventually got out into the tall grass that was knee high,and I lost all interest in watching them. I'm guessing the black snake won,though. They usually do.