"States rights" is a pretty badly misunderstood concept, and not really one I got until I went to law school. Semi-conservative professor on or about the first day says, off-the-cuff, "and you know, states are sovereign, you guys get that, right?"
Me, proud Republican, graduate of fine state university, widely read in politics and history:
"Duh, no."
I didn't.
I had NO CLUE what the actual division of power between states and the federal government was. Not surprising: nobody really teaches it, because it would just make you mad to understand it. Under our Constitutional system, the "base" governments ARE the state governments. The federal government is supposed to limited to powers "enumerated," i.e., listed, in the Constitution. In other words, states are "sovereign" like a KING is sovereign, meaning, it's got the power to do WHATEVER it wants WHENEVER it wants, period. It's the all-powerful. The founding fathers literally saw Massachussetts and South Carolina as versions of England and France --- like countries. And the federal government was like a European Union.
A formula for understanding:
1. States can do whatever they want, except what the Constitution says they can't.
2. The Federal Government can't do anything, except what the Constitution says it can.
Can you believe that?
So how does the federal government end up running our whole lives?
Legal trickery is the answer, starting in FDR's time and continuing until today.