I frequent a Hardy Palm message board where a couple of members insist that there are native alligators in Tennessee (despite the fact that none of the range maps I've ever seen show them there). I have seen a large range extension in Arkansas, due mainly to "restocking" by the state and IMHO, subsequent dispersal. So maybe alligators are there now when there weren't historically?
Here is a televison story about alligators across the state line in nearby MS. It is full of "facts" including the skeleton of a horse killed by an alligator!
TV News Story


