It was found in the state of Virginia, on the east coast of the United States.
I think it might be a species of Fritillary. Below is a picture of a Marsh Fritillary.
Marsh fritillary. Source: Butterfly Conservation.org
I do not think it is a woolly bear or giant leopard moth, just because the hairs seems too sparse for a woolly bear and it lacks the distinct red striping of the giant leopard moth caterpillar. It does not seem to be arctiinae to me.
It's Woolly Bear Caterpillar: http://en.wikipedia.org/wiki/Pyrrharctia_isabella