Originally Posted by MattBrick

Ok, I see your point.
Let's take it from here. Do you understand the distinction between black and white? Most people ini the US do, and can tell by seeing a person in most cases. Black includes African-American/afro-American, which you describe above. It also includes immigrant ethnic groups, and others with black african ancestry. Most people in the US, black and white, consider this to be "black", or at least one meaning of the term. They also typically include most "mixed-race" individuals, like Barack Obama,who were formerly called "mullatto". Let's take this surface definition as our usage for black in the discussion.

Another interesting point you make, is that the afro-american ethnicity, one of the largest, oldest, and perhaps most heterogeneous groups in America, genetically is part European. European ethnic groups in the US, on the other hand would tend to have very little if any mixed african descent. So that is the destinction we are making here.