There once was a term used that distinguished the offspring of a black and white marriage - a mullato (sp?).
Now Africa is a continent, and someone from that continent can, I suppose, call themselves, "African". But "African" is NOT a "race". Would not a "Caucasian" farmer from South Africa (now THERE's a dying species) who migrates -- legally, hopefully -- to the United States not be able to call themselves, "African-American" with a straight face?
The big O is in no sense an "african-American"! He is a Kenyon through his father who was a muslim Arab. The name tells all. As to being an American, that remains to be seen - maybe (I hope) the USSC will straighten out that fact.
Nobody was calling themselves African-American until the MSM broadcast ROOTS.