In last Sunday's New York Times, Paul Campos (a professor at the University of Colorado law school) says that "the gap between black and white Americans at every income level, remains every bit as extreme as it was five decades ago." He shows figures of the income ratio of households at the 20th, 40th, 60th, 80th, and 95th percentiles of the black and white income distribution, and they are indeed all virtually unchanged.
Here is a figure he didn't show: the ratio of per-capita income for blacks relative to per-capita income for whites.
What is the best way to measure the "gap between black and white Americans?" You could argue that per-capita income is not the ideal measure--maybe it should be adjusted for age--but it certainly would involve people rather than households.
Campos's general point is that the slow growth of incomes for working-class and middle-class whites in the last couple of decades isn't because blacks have been doing well. This is true--the only group that has had rapid income growth recently is people with high incomes. But the gap in black and white incomes has declined, although the decline has been slow.
PS: The Census data black and white income is at