Morril tariff doubled the percentages within 2 years.
Northern business interests saw it coming and visited Lincoln in March on 1861.
Remember his comment....” but what about my tariff?”.
He sent the warships south within a few weeks of his inauguration.
But there was no Morrill tariff so long as Southern Democrats dominated Congress and the Presidency.
Even in 1861, Morrill could not pass Congress until Confederate state representatives & senators walked out.
Further, the original Morrill proposals were quite modest, raising average rates from circa 15% to 20%, still relatively low compared to historical numbers.
But after Deep South representatives walked out, and after winds of war began to blow, then Congress, in its wisdom, saw fit not only to pass Morrill, but to raise its rates well above previous proposals.
So DiogenesLamp's argument here is that high Morrill tariffs, in normal peace-time, would have driven 90% of Northern trade, not just south, but specifically to the port of Charleston, SC.
I'm only saying Morrill rates were only especially high because, A) the Deep South had left Congress and B) from its beginning in early 1861 the Confederacy provoked war, and Congress wanted revenues to support whatever responses might be necessary.
Bottom line: in a peacetime situation, Congress could just as quickly reduce tariff rates to match those of the Confederacy, which were roughly the pre-Morrill rate of 15%.
PeaRidge: "He sent the warships south within a few weeks of his inauguration."
In fact, only one "warship", revenue cutter Harriet Lane (crew of 95), arrived at Charleston to witness the beginnings of Confederate military assault on Fort Sumter.
Harriet Lane escorted a civilian steamer, SS Baltic, which carried supplies for Fort Sumter and around 200 US Army troops.
Those troops were ordered not to reinforce Sumter so long as there was no Confederate resistance.
So, Lincoln's mission to Fort Sumter was precisely the same as President Buchanan's mission in January 1861 -- to send enough supplies to allow the garrison there to hold out while negotiations continued.
Lincoln had hoped to trade Sumter for something important, like a state, say, Virginia.
Finally remember, Buchanan's resupply ship, Star of the West had turned back after coming under fire from Confederate cannon.
Lincoln only hoped that a more robust mission might drive (or sneak) through such fire and reach Fort Sumter.
Lincoln was wrong about that, but there's still no justification for endless pro-Confederate wet dreams regarding Lincoln's supposed ulterior motives.