For what reasons did seven southern states secede from the Union shortly after Lincoln's election in 1860?

The American Civil War was the culmination of more than a century of debate in the United States regarding the institution of slavery. An abolitionist movement comprised primarily of Quakers emerged in North America during the 17th century and the issue of slavery was heatedly and repeatedly debated during the Constitutional Conventions with the division between northern and southern colonies already taking shape. The seeming intractability of the issue resulted in it remaining unresolved. The South’s intransigence forced the northern states to accede, at least temporarily, to southern demands in the interest of developing a sense of national unity among the colonies.

While slavery was the key issue dividing the North from the South, the broader issue of “states’ rights” provided the foundation for much of the political debate that took place during the 19th century. What that means is that a debate over the power of the federal or central government relative to the power enjoyed by the individual states remained highly divisive, with slavery representing the single most pressing “state right.” The southern states remained adamant that they be allowed to continue to own slaves because the region’s agricultural industry profited from the free labor. As the 19th century progressed, however, the abolitionist movement in the North grew and pressure from Britain, which outlawed slavery in 1833, to similarly ban the practice also increased.

The election of Abraham Lincoln to the presidency served as a final warning to the South that the Union’s patience with the South over the issue of slavery had exhausted itself. Slavery was only finally abolished with the Emancipation Proclamation signed by President Lincoln—a proclamation rejected by the southern states. The Civil War ended the matter in the North’s favor.