1) Slavery: The most significant cause of the war was the issue of slavery. The southern states were largely dependent on an agrarian economy based on slave labor, while the northern states were more industrialized and opposed slavery. The tensions between the two sides grew as the southern states sought to expand their slave-based economy into new territories, while the northern states opposed this expansion.
2) States' Rights: Another key reason for the war was the issue of states' rights. The southern states believed that they had the right to make their own laws and decide their own policies, including the right to own slaves. The northern states, on the other hand, believed that the federal government should have the power to regulate slavery and other issues. This conflict over states' rights was a major contributing factor to the war.
3) Economic Differences: The third main reason for the war was economic differences between the northern and southern states. The northern states were more industrialized and had a more diversified economy, while the southern states were largely dependent on agriculture and slave labor. This led to disagreements over trade policies, tariffs, and other economic issues, further exacerbating tensions between the two regions.