Perhaps you forgot about inflation. Here are some figures on net imports in 1860 dollars from an old post of mine.
Tariff rates are from Table 1 of Taussig's The Tariff History of the United States, 1910 edition: Taussig.
Yearly customs income is from Table 3 of Taussig. Same link as above. Actually, income from collected import duties was a bit lower than Customs income, but I'll use the higher figures.
Inflation rate was from Inflation Rates. I've seen higher rates than these posted for the period, but I'll be conservative and use these.
After applying the tariff rates to the revenue to determine the value of the imports, I then adjusted the number by the inflation figure. I find that the value of imports to the North relative to the total 1860 import value was:
1860: 1.00
1861: 0.82
1862: 0.50
1863: 0.52
1864: 0.54
1865: 0.38
Thomas Prentice Kettell published Southern Wealth and Northern Profits in 1860. It broke down the distribution of imports to regions by consumption. For 1859, it calculates Southern consumption of imports as $106,000,000, Western consumption as $63,000,000, and Northern consumption of imports as $149,000,000. Kettell bases the split among regions on Treasury figures from 1856.
By his figures the North and West (i.e., Michigan, Illinois, etc.) were consuming 67% of the imports in 1860. The inflation adjusted tariff income above suggests that the high tariff might have indeed reduced the imports to those regions.
Incidentally, Kettell also estimates that the North sent $240,000,000 in domestic goods (whose prices were higher because of the tariff no doubt) to the South in 1859, and that the South paid to the North some $63,000,000 in interest and brokerage.
Thomas Prentice Kettell published Southern Wealth and Northern Profits in 1860. It broke down the distribution of imports to regions by consumption. For 1859, it calculates Southern consumption of imports as $106,000,000, Western consumption as $63,000,000, and Northern consumption of imports as $149,000,000. Kettell bases the split among regions on Treasury figures from 1856.
And in his speech to the Georgia legislature Alexander Stephens, quoting unnamed government documents, put the figure at three-quarters. But by either account, it's clear that the North did generate the large percentage of tariff receipts.
Incidentally, Kettell also estimates that the North sent $240,000,000 in domestic goods (whose prices were higher because of the tariff no doubt) to the South in 1859...
Does Kettell estimate the amount of domestic goods sold outside of the South? Not all goods had their prices inflated by tariffs, of course, but those tariffs fell on all consumers and not just those in the South. If the North consumed proportionate amount pf those protected goods, as they consumed the bulk of imports, then it could be said that the tariff hit all regions equally could it not?
...and that the South paid to the North some $63,000,000 in interest and brokerage.
Was that interest and brokerage costs relating to their primary industry, plantation agriculture? Or was that on the goods purchased from the North. If the former then it was the cost of a service provided by Northern businesses, and the cost of which would have been paid by the ultimate consumer of the cotton or what have you, would it not? If the latter then it would be interesting to see what the similar costs were to Northern and Mid-Western consumers.