Giving credit where it's due: I think that is exactly correct.
Cotton exports alone accounted for more than half of total US exports in 1860 -- that is neither exaggerating nor minimizing.
But other exports, including "specie" (gold & silver) from new mines out west, were not insignificant, and were growing.
PeaRidge quoting New York Herald 3/28/1861: "... imports here will be cut down to an insignificant figure; and the manufactures in the New England States will be seriously damaged; both business houses and factories will be transferred to the South; and, in fact, the northern tariff adopted to protect the manufacturing interests of the North will have no interests left to protect.
The actual effect of the tariff, then, will be to reduce the revenues of the Government at Washington and increase the revenues of the Southern Government..."
This assumes that, in a normal course of events, Congress would do nothing to improve competitiveness of Northern ports.
Matching Confederate rates would be a simple step.
still quoting New York Herald: "...Thus we find the country involved in a fearful commercial revolution through the policy of a fanatical party, which, for thirty years, has been endeavoring to overthrow all the best interests of the Republic for the sake of an abstraction."
So, what does that mean?
Well, in 1861 the New York Herald was New York's most popular newspaper -- pro-Democrat.
That means they were very friendly to their Southern Democrat allies and staunchly opposed to Republicans.
In that effort, we might expect the Herald to exaggerate Republican dangers and minimize Southern Democrat threats.
So in this case the "fanatical party" they refer to is not Fire Eating Southern Democrat secessionists, but rather Northern Republicans, which the Herald claims has been "...for thirty years... endeavoring to overthrow all the best interests of the Republic for the sake of an abstraction."
In 1860 the Republican Party was about seven years old, had only run in two presidential elections.
So who was that party "for thirty years"?
Pre-Republican Whigs were not anti-slavery, far from it.
Both elected Whig presidents (Harrison & Taylor) were Southern slave-holders.
And Republicans were not opposed to "an abstraction", far from it.
In 1860, Republicans were opposed to expanding slavery into those territories which didn't want it.
That's hardly an "abstraction".
This overlooks the fact that those protectionist tariffs were imposed because the Northern manufacturing did not compete very well with English and European manufacturing in a free trade market.
Congress could not magically wish those economic realities away.
Bro tells us: “But other exports, including “specie” (gold & silver) from new mines out west, were not insignificant, and were growing.”
Bro, source please.
Bro comes up with this as a pathway to remaining competitive: “Matching Confederate (tariff) rates would be a simple step.”
Correct Bro, but given the choice between calling Congress into session to do that, or leaving them out of any effort to follow the Constitution, the Executive chose to sent war ships South.
So according to your logic, the Executive was not very smart in starting the war.
And you would be correct, Sir.