Props to the Scandinavian countries. They are the reference, as always.
I seem to recall (but am too lazy to look up) some interesting research on the gini coefficient for subgroups in the United States; if I recall correctly (and it is very likely I don't), Scandinavian Americans as-a-group have a lower gini coefficient than Scandinavians.
That is either evidence for economic oppression of underprivileged groups in the US, or evidence that culture matters when it comes to economic success, depending on whether you're left-leaning or right-leaning.