What adds to the spooky atmosphere are the swamps, which of course is where the alligators live. Also flying around the swamps are huge mosquitoes that look like vampires and bite you, too. You can even hear banjo frogs along the coast as far north as Virginia Beach just north of the Dismal Swamp. In the dark you can hear all these creepy sounds keeping you awake. The swamps are alive.
The carved faces on the trees are supposed to be tree spirits.
The churchyard at St. Simons Island has a legend about the light that appears and disappears in the cemetery. I'll include photos of that, too.
In conclusion: In America I think it's frequently the setting or the natural scenery that's scary. In Europe it's the history.