Your questions are going nowhere.
I think that we're getting bogged down in a discusson of the harbor characteristcs of Charleston, as if that's the only southern port worth mentioning. Clearly, from the figures presented in the document you linked to a while back, New Orleans was by far the more important southern port. Therefore, I think that when you present numbers for New York vs. Charleston, it's not as illuminating a comparison as New York vs. New Orleans would be.