right there's not been a NATIVE american gm, I think, ever. so therefore... everyone of america's strong chess player; today or yesteryears... are from somewhere else.
and anyways, if the person represents where he was raised and not where he lives; why can't we claim Carauna? by the op's logic Carauna is the best US chess player...
....the others - playing for the US - are from Asia and Russia.
Very strange for a country with 320M citizens.