Barack Obama, the first "postracial candidate," is heading to the Democratic nomination almost entirely because of his near-universal support from black voters in the Democratic primaries. In both states Tuesday, his share of that vote was 90% or more. If one resets the black vote to the norm of earlier elections, Hillary Clinton is the nominee. The idea that Obama was a postracial politician dates to his famous keynote speech at the Democratic Convention in 2004. He set the postracial template himself in the speech's third sentence, describing his father born in a small Kenyan village, herding goats, etc. His...