I recently acquired some rare bills that are well taken care of. I have done a lot of research on what to do look for on the currency, where they come from, how to tell if they are real, what certain things mean, and so on. What I cannot find is if there is a way to tell if the money has been circulated or not. It is most likely the bill has been circulated but I am very curious about it still. Any collectors on here that can tell me how find that out or what to look for?