"This suggests that the income gap is not exploding the way the wealth gap was," said Roderick Harrison, a Howard University sociologist who once headed the Census Bureau's racial statistics branch. "It's in fact declining with population size, though clearly not as rapidly."
For the time being, the country is broadly divided between the relative prosperity enjoyed by many whites and Asians, and the economic difficulties experienced by many blacks and Hispanics.
Whites and Asians have higher education levels and are more likely to be part of households in which two adults hold well-paying jobs. A sizable number hold advanced degrees in science and technical fields that pay high salaries, while blacks and Hispanics tend to get degrees in the social sciences and humanities.
More than half of white and Asian households consist of married couples; in contrast, one in five black households are headed by single parents, and just 28 percent consist of married couples.
With a median age of 42, whites are more likely to be in their peak earning years than Hispanics, whose median age is 27, or blacks, at 31.
And Hispanics in particular are more apt to be recent immigrants, many of whom work at low-paying jobs.
But those factors do not fully explain the stubborn chasm.
"The big factor is historical," said Austin Nichols, an economist with the Urban Institute. "If you amass wealth in one group, it tends to stay there. The Hispanic population has grown tremendously over 30 years, and new arrivals haven't had time to amass that wealth."
The recession underscored the significance of education. College graduates had significantly lower unemployment rates than people with no more than a high school degree.
"Your social class — where you came from, your education, family wealth, who you're married to and what they do for a living — is much more important than race and ethnicity" as a factor in income, said Timothy Smeeding, a University of Wisconsin at Madison professor who heads the Institute for Research on Poverty and who studies income inequality.
"There are differences of race and ethnicity, and those were exacerbated by the recession. But what really determines your income has more to do with your education and how long you've been somewhere."