Do you recall that South Carolina threatened to secede in the late 1830s because of high tariffs? Gunboats were sent to the coast, troops were mobilized, South Carolina authorized the purchase of arms to fight a northern invasion, and only when the north sought compromise on the issue did South Carolina back down. We almost fought a Civil War in the late 1830s and it had nothing -- zip, zero, nada -- to do with slavery.
So now you know why tariffs had peaked in the 1820s and 1830s and were lower by the time of the Civil War, when they were raised again. Did you even read the article to note that the Morrell bill tripled the tariff, and that they were soon to be raised even more?
Yes, slavery was an issue, but it was by no means the only issue. Remember (assuming you ever knew) that 4 of the 13 Union states -- plus the chunk of Virginia that later became West Virginia -- were slaveholding states. Remember also that slavery was allowed to continue in the north and the occupied portions of the southern states until almost a year after the war ended.
Look up what I said in any good history book or check it out on the web. You should review your history before making such an embarassing post. Don't bother to respond until you've done your homework.
"In the momentous step which our State has taken of dissolving its connection with the government of which we so long formed a part, it is but just that we should declare the prominent reasons which have induced our course. Our position is thoroughly identified with the institution of slavery-- the greatest material interest of the world. Its labor supplies the product which constitutes by far the largest and most important portions of commerce of the earth. "
Looks like the rebels disagree with you. They say it was slavery, not tarrifs.
Here's a good history book for you. "Lifeline of the Confederacy: Blockade Running During the Civil War" by Stephen Wise. In it he gives a table that showed over 95% of all tariff income was collected in three Northern ports - New York, Boston, and Philadelphia. How could tariffs be such a bone of contention when the overwhelming majority of them were paid by northerners?