I cited sources that said your hypothesis is completely wrong.
Ok, evidence that states' rights was an issue from Day 1:
The Great CompromiseWiki
and 3/5 Compromise were early constitutional disputes over how to manage each state's individual influence in the government. The Supremacy ClauseWiki
was added to stop states from using states' rights, yet interpretation of this clause to prevent nullification didn't happen until 1958.
Of course, the first mention of secession of a southern state was after the passage of the Alien and Sedition Acts: Jefferson advocated nullification and at one point drafted a threat for Kentucky to secede.Wiki
This, of course, had absolutely nothing to do with slavery. However, when slavery became a major issue, the northern states cited Kentucky and Virginia's resolutions during this crisis as a precedent for ignoring the fugitive slave laws: Years later, the passage of the Fugitive Slave Act of 1850 led anti-slavery activists to quote the Resolutions to support their calls on Northern states to nullify what they considered unconstitutional enforcement of the law.Wiki
The consequence? The long-term importance of the Resolutions lies not in their attack on the Alien and Sedition Acts, but rather in their strong statements of states' rights theory, which led to the rather different concepts of nullification and interposition.Wiki
Later, during the War of 1812, much of New England threatened secession: American prosecution of the war suffered from its unpopularity, especially in New England, where anti-war speakers were vocal[. . .]The failure of New England to provide militia units or financial support was a serious blow. Threats of secession by New England states were loud, as evidenced by the Hartford Convention.Wiki
This, too, had nothing to do with slavery.
Secession was brought up once again during the Nullification Crisis. This, of course, was completely about slavery. Just kidding! It was about taxes.Wiki
South Carolina declared the taxes unconstitutional, and threatened to secede: The convention declared that the tariffs of 1828 and 1832 were unconstitutional and unenforceable within the state of South Carolina after February 1, 1833. They said that attempts to use force to collect the taxes would lead to the state’s secession.Wiki
and In the public debate over the Nullification Crisis the separate issue of secession was also discussed. James Madison, often referred to as "The Father of the Constitution", strongly opposed the argument that secession was permitted by the Constitution.Wiki
This was a game-changer for states' rightsWiki
(these are all quotes):
- Nationalists such as Calhoun were forced by the increasing power of such leaders to retreat from their previous positions and adopt, in the words of Ellis, "an even more extreme version of the states' rights doctrine" in order to maintain political significance within South Carolina.
- "I consider the tariff act as the occasion, rather than the real cause of the present unhappy state of things. The truth can no longer be disguised, that the peculiar domestick [sic] institution of the Southern States and the consequent direction which that and her soil have given to her industry, has placed them in regard to taxation and appropriations in opposite relation to the majority of the Union, against the danger of which, if there be no protective power in the reserved rights of the states they must in the end be forced to rebel, or, submit to have their paramount interests sacrificed"
- In July 1831 the States Rights and Free Trade Association was formed in Charleston and expanded throughout the state. Unlike state political organizations in the past, which were led by the South Carolina planter aristocracy, this group appealed to all segments of the population, including non-slaveholder farmers, small slaveholders, and the Charleston non-agricultural class. Governor Hamilton was instrumental in seeing that the association, which was both a political and a social organization, expanded throughout the state.
- Forest McDonald, describing the split over nullification among proponents of states rights, wrote, “The doctrine of states’ rights, as embraced by most Americans, was not concerned exclusively, or even primarily with state resistance to federal authority.” But, by the end of the nullification crisis, many southerners started to question whether the Jacksonian Democrats still represented Southern interests.
- Richard Ellis argues that the end of the crisis signified the beginning of a new era. Within the states’ rights movement, the traditional desire for simply “a weak, inactive, and frugal government” was challenged. Ellis states that “in the years leading up to the Civil War the nullifiers and their pro-slavery allies used the doctrine of states’ rights and state sovereignty in such a way as to try to expand the powers of the federal government so that it could more effectively protect the peculiar institution.” By the 1850s, states’ rights had become a call for state equality under the Constitution.
During the crisis, President Jackson hit the nail on the head. On May 1, 1833, Jackson wrote of nullification, "the tariff was only a pretext, and disunion and southern confederacy the real object. The next pretext will be the negro, or slavery question."Wiki
Of course, when the issue of slavery did rise to prominence, the first to propose secession were northerners!Wiki
It wasn't until a few years later that the idea began to gain traction in the south.
Yes, the states that seceded cited slavery in their resolutions. However, if states had seceded over the Alien and Sedition Acts, they would have cited the Alien and Sedition Acts. If states had seceded over the War of 1812, they would have cited the War of 1812. Had states seceded over the Tariff of Abominations, they would have cited the Tariff of Abominations.
Again, saying the Civil War was only about slavery is like saying the American Revolution was only about taxes and tea. The truth is that states' rights and secession were ongoing issues from Day 1, and the creation of the CSA (and subsequent war) was simply the only time that anyone succeeded.