As much as I hate snakes I will admit we do not have a large population of poisonous ones. We do have some but nothing like other folks. I am on the rocky river bluffs and we have the big SOB timber rattlers but not a huge population. There are massasauga rattlesnakes in large populations some places. There are reports of cottonmouth but I do not know of any confirmation. The rattlers are confirmed as there are videos of folks "hunting" them. Of course they cannot kill them as that would be wrong......
Probably40 years ago there were rumors of folks saying we had coral snakes but that was just BS.
As for rattlesnakes that is a funny subject. In Illinois they are considered threatened and therefore protected. You are not supposed to kill them but i doubt anyone has every been cited for it. You can however remove them alive. As I type this, one of my sons is down in Missouri at the Rutledge Gun and Dog Swap Meet. For years it was a total free for all of hillbilly trading. You would walk around and there were vendors with cattle tanks containing rattlesnakes and other oddities. You pick out the snake you want, pay for it, come back later and it was cooked for you. I just texted my son asking if he had seen any today. Probably 15 years ago the gun trading and other stuff got so out of hand the ATF came in and shut them down.