Final answer:
Economic, political, and social differences between the North's industrial economy and the South's slavery-based agricultural economy, along with opposing views on states' rights and the federal government's role in regulating slavery, fostered the sectional divides that led to the Civil War.
Step-by-step explanation:
The economic differences between the North and the South before the Civil War were stark: the South relied on an agricultural economy supported by slavery, while the North developed an industrial economy with a wage-labor force. Politically, these regions differed over states' rights and the balance of power regarding the federal government and its ability to regulate or abolish slavery. Socially, the North and the South had divergent views on the institution of slavery, leading to heightened sectional tensions as the country expanded westward. Events such as the Missouri Compromise, the Kansas-Nebraska Act, the Dred Scott decision, and the election of Abraham Lincoln escalated these conflicts, contributing to the secession of Southern states and the onset of the Civil War.