Many of the declaration of causes of secession are eloquently written, and far too many people are so dazzled by the style, that they can't see the substance. The primary issue in the secession movement in the deep South was slavery. The documents justifying their actions was couched in high-flown language, but, once again, when you wipe away all the bugle-juice, it gets down to slavery.
The upper South states? That's a whole other issue.