While I agree with the facts of the first answer to this question, I struggle to wholeheartedly blame the institution of slavery for bringing about the Civil War. It's impossible to argue with the facts presented in the prior answer to this question. Slavery was indeed the moral issue of the day; however, we must be careful not to oversimplify the underlying rift between North and South.
Southerners were, generally speaking of course, more politically conservative than Northerners. This is a trend that exists even today. The Bible Belt exists in the southern region of the U.S. and the Christian revivals that took place in the South prior to the Civil War indicate an overall devotion to faith and conservatism that was distinct from the North.
We must also not forget the largely rural setting of the South and the much more urban setting of the North as another factor. Southerners had to rely on themselves much more in their environment, and the threat of revolting slaves on farms/plantations always gave southern culture a flavor of violence. This, coupled with staunch adherence to Biblical conservatism, fostered an independent spirit that made the South antagonistic toward any type of large scale reform. Reducing the spread of slavery into newly organized territories just happened to be the reform that Southerners saw as contrary to the American spirit. The formation of the Republican party and the swift presidential rise of an obscure senator from Illinois was also, while not a reform to policy, a big enough change for the South to resist.
Another note to consider is that the Antebellum world was a world much larger than our own. Leading statesmen were more loyal to their own states than to the overall union. So when the tension over national politics reached fever pitch, Southerners opted for succession rather than continue to be part of a Union that they saw as optional.
In conclusion, we must not always be so quick to blame slavery wholeheartedly for bringing about the Civil War. Slavery just happened to be the fuse that ignited the powder keg of the Civil War, a Civil War decades in the making over differences in both character and culture between North and South. All of the factors that contributed to the divide between North and South should not go unnoticed if one wants a more complete view of US history.
Almost all of the political arguments between the North and the South in the antebellum period (period before the Civil War) had to do with slavery. There is only one major dispute that was not based on that issue.
The one dispute that was not based on slavery had to do with tariffs. In 1828, the US Congress passed a tariff placing high taxes on imported goods. This was, in general, good for the North and bad for the South. It was good for the North because the North had a fair amount of industry and did not need to import very many goods. It was bad for the South because the South’s economy was almost totally based on agriculture. The South got most of its goods by importing them from Europe. The tariff, then, made the South have to pay more for all their goods. When Congress passed this tariff, South Carolina tried to “nullify” it, claiming it was unconstitutional. The North and South argued about the tariff and about whether states could nullify federal laws.
All of the other disputes between the two regions, however, had to do with slavery. For example, in both 1820 and 1850, the North and South argued about whether slavery would be allowed in new territories of the country. In 1850, the two regions also argued about whether Northern states had to help return escaped slaves to their masters. In 1854, the two sides argued about whether there would be slavery in Kansas. All of these arguments came about because the South had slavery and the North did not.
Thus, we can say that all of the political arguments between the two sides after the tariff issue had to do with slavery.