"Partially black" wasn't a thing until Obama got elected.  Historically "one drop of blood" was quite enough to make a person black. 3/4ths white wasn't white, that person was a "quadroon". 7/8ths white wasn't white, that person was an "octaroon." Which half of the bus do you think Obama would have been on in 1950? There was no "partially black" section.

I'm not trying to be snotty-I'm genuinely curious. Republicans have been insisting that he's not really black for 8 years. How come?