The primary cause of the Civil War was slavery, which created deep divisions between the Northern and Southern states.

The South's economy heavily relied on slave labor for its agricultural output, particularly in cotton production. In contrast, the North was becoming more industrialized and favored the abolition of slavery. While issues like states' rights and economic differences played significant roles, slavery was the central issue that fueled tensions. The election of Abraham Lincoln in 1860, who opposed the spread of slavery, intensified these conflicts, leading to secession and war.