You don’t pay attention to detail. The Navigation Act applied to shipping between US ports, so Southerners could send cotton to Europe on whatever ships they wanted. Indeed most cotton that went overseas did go out through Southern ports. The Warehousing Act didn’t apply to exports, so there was no unfair Northern advantage their either.
Am very much aware of that. Several years ago was involved in a discussion with someone who said their family was involved in the shipping business in the Northeast, and they explained how the whole thing worked. I think it may have been rust bucket.
Disallowing ships to go from port to port made it uneconomical for an oceangoing vessel because they could only take on a full cargo at ports like New Orleans. The packet shipping system which was ran by New York, would move from port to port acquiring enough cargo which they would then deliver to an ocean crossing vessel. Alternatively it could be an ocean crossing vessel going from port to port collecting cargo, though my reading indicates the packet system was the dominant method.
With foreign ships unable to do this, it wasn't cost effective to go anywhere but New Orleans, and of course all those contracts were bought up by New York interests.
Indeed most cotton that went overseas did go out through Southern ports.
Through New Orleans mostly. New Orleans was the primary shipping hub for all cotton produced anywhere near the Mississippi river, which was a vast area.
All of it was controlled by New York.