I have heard the debate about whether the CW was from the issue of states rights or the issue of slavery. My contention is that it is both. Before the CW, the country was more referred to as, These United States, which does suggest a type of plurality that would have a significant aspect of governance in states rights (after the CW, we were more referred to as The United States, giving a leaning toward Federal government). The issue of slavery had been a dynamic one. The country was divisive over slavery from the early years and that divisiveness grew as decades unfolded. As this issue grew neither the pro-slavery politicians nor the pro-free politicians wanted to be in the minority. And there was the effort to keep the number of free states and slave states equal. Maine's formation is one obvious example. So, while slavery was a state's right from our beginnings, it was also a growing contentious federal issue. As the world around The Union continued to abolish slavery (Mexico in 1820s, England in 1830s, France in 1840s), the issue of Slavery continued to create a growing schism, which was bringing more and more attention to the Federal Gov't. Lincoln was strongly against the Kansas-Nebraska Act provisions, while also stating several times before and during his early presidency that he would leave slavery alone in the states, where it had already been ratified and accepted by the federal government (His hope was that it would whither away and die through world opinion becoming more and more agains slavery. Bloody Kansas in the 1850s was like a type of microcosm of what was coming. The repeal of the Missouri Compromise brought the ire of many politicians while other politicians worked to keep it appealed through Stephen Douglas's "Popular Sovereignty". So, my contention, is that The CW came about as a result of the blurry lines that had unfolded with regards to states rights, territory's rights, federal laws and the growing ethical and moral world movement of abolishing slavery. It was not one or the other, it was both along with other disagreements - however, I would suggest that these "other disagreements" were exacerbated from this great BIG issue of slavery. Would love to hear your responses.