[RedEyeJack]

Having thought about this topic off and on for some time the following definitions have seemed to arise from the way the terms are used...

Negro - a race. A person like Obama with parents of different races is biracial. He/she is a Negro based on his/her genes.

African-American - A person whose social and cultural values and beliefs are based on the unique (but apparently still developing) amalgam of post-slavery African culture and values and the non-African American culture. Defined by how they live (diet, religion, dress, etc.). He/she is an African-American based on how they live.

Black - A political movement/vision started in the 1960's as a way of focusing voting power in order to achieve political/economic gain. Black-Power was a revolutionary concept that forced the American political leaders to address the needs of both Negroes and African-Americans. It appears to have devolved into a political spoils system with racist over tones similar, ironically, to the segregation system in the Southern states that it helped to end.

Have at it!

[Nakota]

The proper description of Obama's mixed race ancestry is "mulatto". But I suppose it is not correct to use that word anymore.