I think it does have something to do with being a sovereign nation at one time.
Did you know that Texas is the only state that can fly its flag at the same level as the American flag? It has something to do with us being a sovereign nation at one time.
In college, I knew a guy named Cowboy. He had the boots, hat and jeans. His accent was pure Texas. I found out one day that he grew up in New York City and had only been living in Texas for a couple of years. Man, he even had me fooled.
I told him if he loves my state that much, he is a Texan as far as I was concerned. You don’t have to be born here to be a Texan. So welcome adopted Texan!
Did you see that King of the Hill where they found out Hank had been born in NYC? (The creators of that show went to Humble High school just down the road from me.)