Which issue was a major problem leading to the Civil War?

The correct response highlights slavery as a principal issue leading to the Civil War due to its deep socio-economic and moral implications in the United States. By the 1860s, the nation was starkly divided between the North, where slavery was increasingly viewed as morally and economically untenable, and the South, where the agrarian economy relied heavily on enslaved labor.

The conflict over slavery's expansion into new territories and states generated significant tension, culminating in various political compromises and disputes, such as the Missouri Compromise and the Kansas-Nebraska Act. The election of Abraham Lincoln in 1860, who was opposed to the spread of slavery, exacerbated fears among Southern states, triggering their secession and leading to the onset of the Civil War.

While issues like taxes, states' rights, and immigration did play roles in the broader scope of American society, they were often intertwined with the debate over slavery. The question of states' rights was fundamentally about whether states had the authority to allow or disallow slavery, while tensions over tariffs and economic policies were often framed within the context of a slave economy. Therefore, slavery remains the most definitive issue that polarized the nation, ultimately serving as the catalyst for conflict.