According to data released by the Census Bureau, black and Asian women with college degrees earn slightly more than similarly educated white women. It is not exactly clear why this disparity exists, but economists suggest that it may have something to do with the tendency of minority women to hold more than one job and the tendency of black professional women to take spend less time out of the workforce when they have children.
See "Black, Asian Women With Degrees Earn More", The New York Times, March 27, 2005