For me, 37 years so far. Longer than most people who were born here... AND, I was 18 when I moved here, so I didn't spend any baby years here. I remember every minute, in other words. :)
We've only been here 8 years. It is the longest I've lived anywhere and I can't imagine living anywhere else in the US at this point. Our only regret is that we didn't do it earlier in our lives. We could have skipped the other states. LOL