You might imagine that, but there's not a one. There are certainly claims of others, economic and constitutional in chief, but these are simply concerns about the preservation of slavery and white supremacy as the enslaving states' social, political, and economic system.

So let's dig into the big ones:

At its root, and also the branches, trunk, leaves, and all the rest of the tree, Civil War the United States experienced is one between the white majority of a section of the country which had a uniquely long and durable commitment to enslaving black Americans for profit and pleasure, a system of rape and torture which they chose to make the central institution of their civilization. The rest of the United States did not do that, though in many cases it's not for lack of trying and sometimes the decision against it is a near-run thing. So all differences between the North and the South are going to come back there; it's literally where the line is drawn. That we are speaking of differences between the American South and elsewhere in the United States means we are speaking of differences which arise exclusively courtesy of the latter's commitment to enslaving people.

It's difficult to go into detail here because there have been so many issues thrown up in bad faith, but probably the most popular of them are state's rights and the tariff. Both of these are, for the South, 100% slavery issues. That's not to say that non-Southerners never have opinions that come roughly in line with or similar to those expressed by the enslavers, but rather that the South's embrace of those issues arises from its proslavery orientation.

State's rights is not a thing. By that, I mean nobody ever embraced the idea because they think there's a platonic ideal of a state government out there which is somehow closer to the Good than the national government. Or even if they did then their apprehension of the Good arises from their ideas of what they want to see in real life. (Otherwise it's simply irrelevant.) If one favor's state government, that means simply that one believes it will produce for oneself outcomes generally preferable to those which seem feasible on the national level at the time of speaking. This is a point lost on no one in the Antebellum and any politician with a career longer than an election cycle will show plenty of reverses of course. These are incomprehensible of state's rights as just desirable in itself. They must be liars at least half the time if we are to take them at their word.

We should not. For one thing, the data already in front of us suggest that they're not being candid. For another, it requires an uncritical examination of our sources and that's just not doing history at all. Our goal is to understand the past, as best we can, and learn from it. It is not simply to act as meat xeroxes for dead racists. Digging down just a few breaths longer, we can look at when those about-faces take place. Southerners are all for the national government when slavery is threatened by foreign foes, so you have otherwise state's rights radicals like John Calhoun and most of the rest of South Carolina's political set all-in on grand national infrastructure projects in the wake of the War of 1812. As the threat of renewed war with the United Kingdom recedes, and the postwar era of antislavery activism gets underway, they flip hard and will spend most of the rest of the decades before Sumter staking out increasingly extreme forms of opposition to any kind of federal power, explicitly because it might be used to enact some kind of emancipation. They and others like them elsewhere in the South make no bones about this. A nation which has the power to enact a high tariff -which the Constitution emphatically permits- might use that money to force enslavers to sell the people they enslave to the nation which will then free them. A nation which has its own bank can make paper money enough to do the same. A nation which bans slavery in a territory ensures that territory comes in as a free state and thus another potential vote for a far-off constitutional amendment abolishing slavery.

To be sure, not every single person makes every single argument and levels of commitment to state's rights rhetoric vary considerably, but they all fail in the face of the simple question: State's rights for what? At this point our sources will often say something about handling their "domestic institutions" or letting each state do as it may...but we know what their states are doing -enslaving people- and they are not remotely keen on letting states who adopt antislavery policies enjoy the same kind of local control. At the eve of the Civil War, the state of Virginia was in the federal courts trying to establish a legal right to bring enslaved people into free states and keep them there indefinitely. Calhoun demanded Northern states censor their mail -they did not- and he and others demanded the suppression of antislavery political groups in the North on a regular basis. The most generous we could honestly say about all this is that Americans in both sections have an instrumental attitude toward local autonomy. The variable that matters for the white South is slavery's security, thus we must in this context view invocations of state's rights as a variant spelling for slavery.

Which brings us to the tariff. Tariffs are a genuinely divisive issue in American politics through the nineteenth century. The South is generally, though not exclusively, against them. They are quite clear about why this is so: a tariff -they will sometimes say a protective tariff, but never articulated just what made one rate protective and another not- is a subsidy from the nation, by which they mean their pockets, to Northern manufacturing interests. (Manufacturing interests in the South don't enter into it, despite their existing in adequate numbers to support a Southern protectionist constituency. Nor do tariffs on stuff like cotton, which the cotton-growing states never find it in themselves to get worked up about. The American sugar industry was completely dependent on tariffs for its profits too.) This is slavery coming and going. Southerners believe that the tariff picks their pockets, which are filled with cash they wrung from the lives of black Americans to subsidize a social and labor system which they then see as a threat to their own. The more the North industrializes, the less like the South it will become and by 1850 -perhaps by 1830, but this is an accelerating trend- it already looks wildly antagonistic toward slavery at least so far as many enslavers are concerned. So Yankees want to cut into the profits of enslaving people in order to build a system which might be a threat to it.

But the tariff is nonsensical on another level which ought to be familiar to any American who managed to remain conscious in high school: a tariff is a law, so it needs to get through Congress. The enslaving states have at least parity in the Senate through 1850 and a workable majority through their greater sectional unity all the way to 1860. The elections that year returned a Congress that did little to change that. The GOP, which was generally in favor of tariffs, retained a majority in the House but failed to gain one in the Senate. Any tariff bill would have to get past the chamber's Democrats, who were almost universally inclined to give the slave states whatever they wanted short of independence. This is not a situation where there's an imminent danger of hiked tariff rates or where the white South might expect to lack its usual veto power over them. There was only way that tariffs would pass that Congress over the South's objections: if the Southern Senators got up and left. They did that and we know the rest.