Your comment about Mobile and New Orleans raises an interesting point. I’ve always assumed that the growth of commerce on the Mississippi River system played a much bigger role in the Civil War than most people realize. The U.S. could not have expanded the way it did if the Union states in the Midwest and (later) the Great Plains could not transport freight freely up and down the Mississippi River.
Rivers were still the easiest way to move goods in bulk at the time. New Orleans was the logical point of export for cotton and other agricultural goods grown in Mississippi, Tennessee, Arkansas and Louisiana. Mobile handled Alabama.