Hi joeyfresh,
That looks very similar to the flint I find on the shores of the Potomac river. If it is flint, then it's likely flint from England. Colonial era ships from England would fill their holds with stone (flint) as ballast for the journey to the new world. They would then dump the stone off before heading into port where they would load up with goods for the trip home. I have found pieces that appear to have been worked.
When I return home at the end of the week I'll be posting pics of an epic day I had on the river where I found over a dozen artifacts and many pieces of flint.