The primary cause of the American Civil War from a political perspective was the contentious issue of slavery and its expansion into new territories. The Southern states, dependent on an agricultural economy that relied on enslaved labor, sought to protect and extend slavery, while Northern states and abolitionists viewed it as a moral evil. The Dispute over states' rights versus federal authority further exacerbated tensions, leading to the secession of Southern states from the Union. This conflict ultimately represented a clash of two distinct social, economic, and political systems.