Whenever there is a Democratic president, Republicans like to oppose him by citing "states' rights." (Funny how that doesn't seem to apply when there is a Republican in the White House.) Some of them go so far as to promote the concept of nullification. We fought a Civil War over that notion, and apparently winning that war wasn't enough to settle that matter.
Well, I just happened to stumble upon a very interesting quote on that subject, and it suggests that, yes, the United States of American is, in fact, a sovereign nation and not a collection of fifty independent fiefdoms loosely joined together by a common currency, much like the Articles of Confederation or the EU.
But here is the remarkable part: The quote is from Southern governor in the 1950s, who initially condemned Brown v. Board of Education. Even better, it is a superlative example of a politician stating his beliefs, standing by them, and asking demanding that he be held accountable for them.