I know the slavery issue is what gets the headlines for the causes of the Civil War. However, when you actually read into history, that is a small
aspect of Southern opposition, not the cause. If Lincoln had not emancipated the slaves and still won, they would not have that to flaunt.
One site I recently read gave 10 reasons in detail which I will list condensed.
1. TARIFF
Prior to the war about 75% of the money to operate the Federal Government was derived from the Southern States via an unfair sectional tariff on
imported goods and 50% of the total 75% was from just 4 Southern states.
2. CENTRALIZATION VERSUS STATES RIGHTS
The Confederate States of America fought to preserve Constitutional Limited Federal Government as established by America's founding fathers who were
primarily Southern Gentlemen from Virginia.
3. CHRISTIANITY VERSUS SECULAR HUMANISM
The South believed in basic Christianity as presented in the Holy Bible. The North had many Secular Humanists (atheists, transcendentalists and
non-Christians). Southerners were afraid of what kind of country America might become if the North had its way.
4. CULTURAL DIFFERENCES
Southerners and Northerners were of different Genetic Lineage's. Southerners were primarily of Western English (original Britons), Scottish, and
Irish lineage (Celtic) whereas Northerners tended to be of Anglo-Saxon and Danish (Viking) extraction.
5. CONTROL OF WESTERN TERRITORIES
The North wanted to control Western States and Territories such as Kansas and Nebraska. They passed laws against slavery that Southerners considered
punitive.
6. NORTHERN INDUSTRIALISTS WANTED THE SOUTH'S RESOURCES
The Northern Industrialists wanted a war to use as an excuse to get the South's resources for pennies on the dollar.
7. SLANDER OF THE SOUTH BY NORTHERN NEWSPAPERS
This political cause ties in to the above listed efforts by New England Industrialists. Beginning about 1830 the Northern Newspapers began to slander
the South.
8. NEW ENGLANDERS ATTEMPTED TO INSTIGATE MASSIVE SLAVE REBELLIONS IN THE SOUTH
Abolitionists were a small but vocal and militant group in New England who demanded instant abolition of slavery in the South
9. SLAVERY
Indirectly slavery was a cause of the war. Most Southerners did not own slaves and would not have fought for the protection of slavery. However they
believed that the North had no Constitutional right to free slaves held by citizens of Sovereign Southern States.
10. NORTHERN AGGRESSION AGAINST SOUTHERN STATES
It was politically important that the South be provoked into firing the first shot so that Lincoln could claim the Confederacy started the war
Source
Additionally, "North and South each entertained different visions for the United States. The South fully embraced Thomas Jefferson's class-based,
agrarian "utopia," and strongly resisted Alexander Hamilton's desire to move the U.S. economy toward banking, commerce, and industry."
Source
From my readings of history, the secession was primarily over states rights and the Southern resources being taken advantage of by Northern business.
The War was 'started' by the South to claim what was on their property.