White adults 25 and older, however, are significantly more likely than blacks to have completed at least a bachelor’s degree – 34 percent versus 21 percent. But in 2010, 38 percent of blacks between the ages of 18 and 24 were enrolled in a university, compared with 43 percent of whites.

On other measures, too, blacks fare poorly. The higher incarceration rates and the dissolution of the black family have particularly hurt black mobility. Blacks are about 3.73 times more likely to be arrested for marijuana possession than whites, despite using the drug at roughly the same rate. Black men were more than six times as likely as white men in 2010 to be incarcerated. In 2011, 478 of every 100,000 white men and 51 of every 100,000 white women were imprisoned. For black men the rate was 3,023 per 100,000 and for black women 129 per 100,000. Former inmates earn less money and have a harder time moving up the economic ladder.

The traditional family has collapsed since the 1960s because of a decline in marriages and an increase in out-of-wedlock births. Blacks lead the way in both. Marriage rates among whites and blacks have declined in the past 50 years. Today about 55 percent of whites and 31 percent of blacks ages 18 and older are married. In 1960, 74 percent of whites and roughly 60 percent of blacks were married. In 2011, 72 percent of black children were born to unwed mothers and 55 percent of black children were being raised by single parents. Such children are four times more likely to be poor than children raised by married parents.

President Obama paid tribute to King’s legacy in a speech that touched on the accomplishments the nation has made on racial equality. He also issued a call to complete the journey to economic equality set forth by the march in 1963.

“We must remind ourselves that the measure of progress for those who marched 50 years ago was not merely how many blacks could join the ranks of millionaires,” Obama said on the steps of the Lincoln Memorial. “It was whether this country would admit all people who were willing to work hard, regardless of race, into the ranks of middle-class life.”

The president urged the nation’s leaders to tackle the problems of income inequality to live up to King’s dream.

“For over a decade, working Americans of all races have seen their wages and incomes stagnate. Even as corporate profits soar, even as the pay of a fortunate few explodes, inequality has steadily risen over the decades. Upward mobility has become harder,” Obama said.

Explanations for these economic disparities fall more or less into two camps: those stressing the lingering effects of racism and those arguing that these gaps are caused by racial differences in human capital.

Ron Haskins and Isabel Sawhill, two Brookings Institution scholars, have found that Americans who finish high school, work full-time, and wait until 21 and married before they have children have a 72 percent chance of joining the middle class and only a 2 percent chance of being poor. Sadly, few blacks meet all three of these basic conditions.

Americans are pessimistic that progress is being made toward King’s goal of racial equality. A Pew Research Center poll found that nearly twice as many blacks than whites say the police treat blacks less fairly. And about three times as many blacks than whites believe blacks are treated less fairly at work, public schools, stores, and courts. In the recent telephone survey of more than 2,200 adults, 44 percent of white respondents said the U.S. had a long way to go before achieving racial equality, compared with 79 percent of black respondents.