>A nation is a stable community of people, formed on the basis of a common language, territory, history, ethnicity, or psychological make-up manifested in a common culture.
California is part of the United States. The nation is United States. Sorry, I know Texans and Californians both think they're big enough to be exceptions, but they're still just states.
The stable community is the USA. We share highways, military resources, language, government, traditions, laws, etc. This is a ridiculous argument.
I highly disagree with this sentiment. Very few of the US institutions are well designed, and I suspect that there will be a decline of American hegemony worldwide.
People can, and frequently do, make distinctions between nations and states. Hence the term "nation-state" to refer to those nations which are also states. If there wasn't a distinction, the combined term wouldn't be necessary.
https://en.wikipedia.org/wiki/Nation
I studied these topics at a university level. A nation is not a legal entity. Sovereignty is a legal property, and it can be applied to nations.