Economic Rape of the South Led to Secession

When Union troops tried to resupply Fort Sumter, South
Carolina fired on the fort. The only casualty was a donkey,
but it gave Lincoln an excuse to call up 75,000 troops to stop
secession and force Southern states to remain in the Union.
Some critics believe he deliberately provoked the battle to
justify the war against the Southern states.

It's important to understand the major role economic issues played in the South's decision to secede. The states of the South represented about one fifth of the U.S. population, but they were paying over 80% of the tariffs levied by a Congress controlled by the Northern states. The actual amount involved according to Charles Adams writing in his book When in the Course of Human Events was about $107.5 million being charged at federal ports on goods coming into the country. The South, more dependent on imports than the mercantile North ended up paying about $90 million of this total compared to $17.5 million from the Northern states. That was a disparity of 83% of tariff taxation being picked up by the South and only about 17% from the North.