The main reasons for the secession of the Southern from the Union were states' rights, unfair taxation and slavery. In general, the states that seceded felt that the laws of the Union were unfair.
Abolitionist groups in the North succeeded in swaying popular opinion in favor of abolishing slavery, and many Northern states outlawed the practice. Business interests in the South, particularly agriculture, remained in favor of slavery because it was advantageous to the economy of the region. The Southern states were concerned about legal provisions that outlawed slavery in newly formed states admitted into the Union.
Slavery was the most prominent issue in the Civil War, but it was not the only source of the conflict. Southern states believed they deserved more sovereignty and wanted to be able to nullify federal laws. Southerners were also upset about taxation laws that were disproportionately beneficial to the Northern states. A belief in Southern nationalism also played a role for citizens with no economic stake in defending slavery. These Southerners sided with the Confederacy, even though they did not own slaves. Abraham Lincoln's presidential election was also a direct trigger for secession. Seven Southern slave states formed the Confederate States of America before Lincoln was inaugurated.