Then, as now, US workers were generally the best paid workers in the world, making US produced goods relatively expensive.
But US tariffs went up & down every few years going all the way back to the beginning, around 1792.
At their highest, tariffs averaged around 35% in the 1830s, under president Andrew Jackson and Vice President Calhoun -- the "tariff of abominations".
At their lowest since then, tariffs reached 13% in 1840 and again 15% in 1860.
Confederate tariffs averaged around 15%.
Point is: for political as well as economic reasons, US tariffs went up & down, without causing major disruptions to either the economy or political alignments.
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.