Separation of church and state is a good thing. Separation of Wall Street and state would be nice as would be separation of race and state. I could name others. It's too bad that the U.S. Census still counts people by race, although it's a good that they finally allow respondents to check more than one box.
Most of us have limited knowledge of the racial/ethnic mix among our many ancestors. But if we want to self-define, fine.
Today's NY Times includes "Black? White? Asian? More Young Americans Choose All of the Above". The piece cites a recent Pew Research Center survey which found that "Nearly 9 percent of all marriages in the U.S. in 2009 were interracial or interethnic, more than double the percentage fo 30 years ago." With any luck, it will keep spreading and doubling.
Tribalism is a scourge. Look at a map of the world's conflicts, now and in years past. They are usually about racial or ethnic differences. Inter-marriage is probably the best way to dispose of them.