Rufus, but why the adjectival modification in the first place? It's perfectly obvious to the naked eye that one is of African or Asian descent. Why qualify or limit one's Americanism unless one values the other more than being American? It is blatantly saying "I'm only part American and that part comes second."
I'm not sure of the first usage, but suspect it originated more to itemize the different varieties of white european immigrants than those of different races. And I don't know if it was a matter of self-identification or condescending labels used by WASPs. Regardless of that, I guess my point is that I don't see it as minimizing anyone's American-ism from a grammatical point of view, how they're intending it to be perceived could be a whole different thing.
