Is the Primary Race Divided By Race?

Hey World,
Obama won the North Carolina primaries, and Hillary Clinton has Indiana. MSNBC says that the race is already divided by racial lines. According to NBC News, an estimated one-third of all ballots were cast by black voters in North Carolina, and Obama claimed support from roughly 90 percent of of these black voters. As for Hillary, the report says, her victory among white voters was just as wide. Do you guys think that the primaries have become divided by race? Is it inevitable that the race is divided by race, so to speak? Or are there other issues involved?