Actually, I don't know if Dave Matthews is an American citizen. But just making a point: the widespread use of the term "African-American" is profoundly misguided. It serves as a reminder of how stifled and irrational conversations regarding race in this country can be.
I don't use the term African-American, and I don't think most people should either. Well, unless I am referring to an American citizen who has immigrated from an African nation. The conventional usage fails for a number of reasons:
1) It is confusing. Lennox Lewis is not an African-American (he's an Englishman of Jamaican heritage). Neither is Tim Duncan (born in the Virgin Islands). Etc. etc. Dave Matthews IS, except it would sound absurd to describe him as such because we all understand "African-American" to mean nothing other than "black."
2) It seems to state a certain "otherness" to one's status as an American. No one describes Bill Clinton as an "Anglo-American" or even Mitt Romney as a "Mormon-American." Why do black people merit such a qualifier?
3) It's seven syllables long. "Black" is just one. I like efficiency (longwinded Waco post below notwithstanding).
This reached, for me, the height of absurdity when I submitted a legal brief to my TA in law school during my first year, describing the facts of a case involving discrimination against a black truck driver. My TA crossed that out and wrote "African-American." I didn't make the change, and this happened again in a second iteration. His explanation- "that's the correct term for legal usage." Now, it may have just been that my TA is an idiot. But it goes to show the power of labeling that "black" could be considered an incorrect word.
Basically, as I understand it, "African-American" is a term for white people to demonstrate that they are not racist. A better idea: just don't be racist.