My bad, also discussing Morrill act with another participant. If the seven states had not seceded when they did the Morrill Tariff act would have never became law.
Not one of those states were effected by it. I doubt they collected the Morrill tariff rates in Charleston after Jan 1861.
I don't usually argue about the Morrill Tariff act. I simply note that the Confederates were going to lay a 13% tariff across the board, rather than the complicated patchwork of tariffs that existed by Federal law.
Whatever was the various Federal tariffs of the Union, 13% is both much lower and much less complicated to deal with, and it would have caused the bulk of import/export traffic to shift to the South.
Another factor that people often ignore is the consequences of the "Navigation act of 1817." It ended up producing a near monopoly on shipping for companies located in the North East. This caused them to raise their prices until it was just barely underneath the fines and penalties for using foreign ships.
Independence for the South would have removed the necessity of complying with this act, and it would have caused a dramatic realignment of the shipping industry. It may have singlehandedly revived the Southern ship building industry.