[smt88]

Assuming this is a sincere question from someone who doesn’t know US history:

States in the US were modeled after sovereign nations, perhaps even more loosely connected than the EU is today. They didn’t even share a currency.

Eventually the federal government became more important and powerful, and there are many federal laws now, but states are fundamentally still their own thing with the rights to do certain things that are more like a sovereign nation than a province.