Spiny soft-shell (Eastern race).
The orginal post is here. The answer is Eastern spiny soft-shelled turtle, juvenile, probably female. Females are larger than males.
There are two species of soft-shelled turtle in the Eastern US. The spiny and the smooth. The difference is that the spiny have little spikes somewhere on their carapace, while the smooth don’t have them at all. Spiny soft-shells are a bit bigger, with females approaching 18 inches in diameter.
Here’s a smooth soft-shell:
The smooths are smaller, with females only approaching 14 inches in diameter.
These turtles can be purchased as pets. I remember as a boy attending a summer science camp at a nearby college. One of the faculty was a herpetologist who kept Burmese pythons, red eared sliders, and, in one tank, a huge (I think spiny) soft shelled turtle. We were told never to let our fingers hang over the edge of the tank, because this turtle could reach its long neck out and bite us.
These turtles are highly aquatic, only coming ashore to lay their eggs and occasionally bask along the river bank. They are by far the fastest of all turtles. I’ve encountered them along river banks in West Virginia running flat-out like rabbits just to hit the water. They are unlike the other big water turtle of this region, the common snapper, which ponderously crawls from its nesting sites to the rivers and ponds.
Here’s video of a young naturalist encountering one and doing his homework:
Video from zombieslayer92. He’s a little off for the sex of the turtle. Its size and proximity to the road suggest it was a gravid female looking for a place to lay her eggs.
