Tariff's?
Five myths about why the South seceded - The Washington Post
2. Secession was about tariffs and taxes.
During the nadir of post-civil-war race relations — the terrible years after 1890 when town after town across the North became all-white
“sundown towns” and state after state across the South prevented African Americans from voting — “anything but slavery” explanations of the Civil War gained traction. To this day Confederate sympathizers successfully float this false claim, along with their preferred name for the conflict: the War Between the States. At the infamous Secession Ball in South Carolina, hosted in December by the Sons of Confederate Veterans, “the main reasons for secession were portrayed as high tariffs and Northern states using Southern tax money to build their own infrastructure,”
The Washington Post reported.
These explanations are flatly wrong. High tariffs had prompted the Nullification Controversy in 1831-33, when, after South Carolina demanded the right to nullify federal laws or secede in protest, President Andrew Jackson threatened force. No state joined the movement, and South Carolina backed down. Tariffs were not an issue in 1860, and Southern states said nothing about them. Why would they?
Southerners had written the tariff of 1857, under which the nation was functioning. Its rates were lower than at any point since 1816.