“The framers of our Constitution never exhausted so much labor, wisdom and forebearance in its formation, and surrounded it with so many guards and securities, if it was to be broken by every member of the Confederacy at will. It was intended for ‘perpetual union’ so expressed in the preamble, and for the establishment of a government, not a compact, which can only be dissolved by revolution, or the consent of all the people in convention assembled. It is idle to talk of secession.” Robert E. Lee - January 23, 1861
If that were true, that would mean any state today could secede if it felt like it. That means some nuts could take over my state of Wisconsin and set up some phony baloney "independent" nation. What we would have then is utter chaos. Because at some point some nuts in any state could do the same thing. All Americans would be held hostage to the lunatics.
And just imagine trying to live in this new nation. You'd have to have new currency, new passports, new everything. In short, the idea of unilateral secession is lunacy. It was lunacy then, it would be lunacy now.
-- Abolishionist Lysander Spooner