As the Seth at Enik Rising reminds us with exit poll results, there were almost no non-white Republicans voting the in South Carolina primary election. About 99% of exit poll respondents were white, while the number of black and other non-white Republican primary voters in South Carolina rounded to 1% each. Overall in South Carolina, as of "the 2010 census, the racial make up of the state is 66.2% White, 5.1% Hispanic, 27.9% Black or African American, 1.3% Asian, and 0.4% Native American."
There are places in the United States where the Republican party is not so monolithic racially, such as Florida which hosts the next Republican primary of the 2012 election a week from today, and California, but South Carolina is not one of them.
The fact that South Carolina Republican primary voters are disproportionately white is not in the least bit surprising. The fact that the Republican party can't claim even 4% of the African American electorate or even 15% of the electorate belonging to other races in South Carolina, or more than 3% of all non-white voters in South Carolina, is more notable. For example, an African American adult is about twice as likely to be incarcerated as he or she is to be a Republican in South Carolina.
This is particularly ironic given the fact that Lincoln, who is still hated by many South Carolina Republicans, was the original Republican President, and that almost all blacks in the Reconstruction South, about one hundred and fifty years ago and for many decades thereafter, were Republicans.