The primary cause of the American Civil War from a political perspective was the contentious issue of *slavery*. Conflicts arose over whether new states admitted to the union would be free or slave states, exacerbating sectional tensions between the North and South. The election of Abraham Lincoln, perceived as anti-slavery, ignited fears among Southern states of losing political control, leading to their secession. This clash between differing economic systems and social ideologies resulted in a deep national divide, with political disputes over states' rights versus federal authority further escalating tensions. Ultimately, these factors culminated in a devastating civil conflict.