The Post's Peter Baker performs a useful mathematical service:

Let's say, for instance, that African American voters represented just 20 percent of the total electorate in South Carolina instead of the 55 percent they did -- closer to, say, their share of the New York Democratic electorate. Assuming each candidate won the same proportionate support within each racial group, then Obama still would have won the primary with 34.6 percent of the overall vote to 32.6 percent for Clinton and 32.4 percent for former North Carolina senator John Edwards.

--Michael Crowley