Without all of the rice, cotton, and sugar plantations, England might have abolished slavery a lot sooner (maybe around the time of Catholic emancipation in 1848).
The United States would have ended up splitting the territory with Mexico or buying the Isle de Orleans from Spain, so you'd have an American port on one side of the river and a foreign port at Algiers Point. Woodville, MS wouldn't be a major city - it's our largest port but only because of its location at an arbitrary international border. (And that would be a great loss, as some of the world's best music developed at Woodville's docks.)