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https://en.wikipedia.org/wiki/Historiographic_issues_about_the_American_Civil_War

Historiography examines how the past has been viewed or interpreted. Historiographic issues about the American Civil War include the name of the war, the origins or causes of the war (slavery or states' rights), and President Abraham Lincoln's views and goals regarding slavery.

The question of how important the tariff was in causing the war stems from the Nullification Crisis, which was South Carolina's attempt to nullify a tariff and lasted from 1828 to 1832. The tariff was low after 1846, and the tariff issue faded into the background by 1860 when secession began. States' rights was the justification for nullification and later secession. The most controversial right claimed by Southern states was the alleged right of Southerners to spread slavery into territories owned by the United States.

Under Lincoln's leadership, the war was fought to preserve the Union. With slavery so deeply divisive, Union leaders by 1862 reached the decision that slavery had to end in order for the Union to be restored. Union war evolved as the war progressed in response to political and military issues, and historians do not use them to explain the causes of the war. The key new issues were the elimination of slavery and the legal and economic status of the freed slaves.

Economic issues