I hope you do understand that the Civil War was NOT started over slavery. It was all about northern greed trampling on states rights. The slavery issue came about far after the war began.
The following states said the following when seceding from the Union:
South Carolina stated reason:
"A geographical line has been drawn across the Union, and all the States north of that line have united in the election of a man to the high office of President of the United States, whose opinions and purposes are hostile to slavery. He is to be entrusted with the administration of the common Government, because he has declared that that “Government cannot endure permanently half slave, half free,” and that the public mind must rest in the belief that slavery is in the course of ultimate extinction. This sectional combination for the submersion of the Constitution, has been aided in some of the States by elevating to citizenship, persons who, by the supreme law of the land, are incapable of becoming citizens; and their votes have been used to inaugurate a new policy, hostile to the South, and destructive of its beliefs and safety."
Mississippi
"Our position is thoroughly identified with the institution of slavery—the greatest material interest of the world. Its labor supplies the product which constitutes by far the largest and most important portions of commerce of the earth. These products are peculiar to the climate verging on the tropical regions, and by an imperious law of nature, none but the black race can bear exposure to the tropical sun. These products have become necessities of the world, and a blow at slavery is a blow at commerce and civilization. That blow has been long aimed at the institution, and was at the point of reaching its consummation. There was no choice left us but submission to the mandates of abolition, or a dissolution of the Union, whose principles had been subverted to work out our ruin …"
Louisiana:
"As a separate republic, Louisiana remembers too well the whisperings of European diplomacy for the abolition of slavery in the times of annexation not to be apprehensive of bolder demonstrations from the same quarter and the North in this country. The people of the slave holding States are bound together by the same necessity and determination to preserve African slavery."
Texas
"… in this free government
all white men are and of right ought to be entitled to equal civil and political rights; that the servitude of the African race, as existing in these States, is mutually beneficial to both bond and free, and is abundantly authorized and justified by the experience of mankind, and the revealed will of the Almighty Creator, as recognized by all Christian nations; while the destruction of the existing relations between the two races, as advocated by our sectional enemies, would bring inevitable calamities upon both and desolation upon the fifteen slave-holding states …"
Alabama
"Upon the principles then announced by Mr. Lincoln and his leading friends, we are bound to expect his administration to be conducted. Hence it is, that in high places, among the Republican party, the election of Mr. Lincoln is hailed, not simply as [a] change of Administration, but as the inauguration of new principles, and a new theory of Government, and even as the downfall of slavery. Therefore it is that the election of Mr. Lincoln cannot be regarded otherwise than a solemn declaration, on the part of a great majority of the Northern people, of hostility to the South, her property and her institutions—nothing less than an open declaration of war—for the triumph of this new theory of Government destroys the property of the South, lays waste her fields, and inaugurates all the horrors of a San Domingo servile insurrection, consigning her citizens to assassinations, and her wives and daughters to pollution and violation, to gratify the lust of half-civilized Africans."
I can also provide hundreds or quotes from pre-war confederate leaders stating explicitly that it was bc of slavery. Again all quotes above are from states explaining why they are leaving.
It was about states rights in the sense that the confederacy wanted the right to enslave people.