and the government is supposed to do exactly what to address this trend?

NYTimes | This week, four presidents journeyed to Austin, Tex., to address the Civil Rights Summit and remark on President Lyndon B. Johnson’s legacy on the 50th anniversary of the passage of the Civil Rights Act.

That landmark act brought an end to legal racial segregation in public places.

But now we are facing another, worsening kind of segregation, one not codified but cultural: We are self-sorting, not only along racial lines but also along educational and income ones, particularly in our big cities.

Our cities are increasingly becoming vast outposts of homogeneity and advantage, arcing ever upward, interspersed by deserts of despair, all of which produces in them some of the highest levels of income inequality ever seen in this country.

Some call this progress; I call it a perversion, at least of the concept of diversity — of race, culture, identity and class — that dynamic engine that built urban identities and that is now being erased out of them.

As a report by Kendra Bischoff of Cornell and Sean F. Reardon of Stanford pointed out last year: “The proportion of families living in affluent neighborhoods more than doubled from 7 percent in 1970 to 15 percent in 2009. Likewise, the proportion of families in poor neighborhoods doubled from 8 percent to 18 percent over the same period.”

This is consistent with a 2012 Pew Research Center report that found, “Residential segregation by income has increased during the past three decades across the United States and in 27 of the nation’s 30 largest major metropolitan areas, according to a new analysis of census tract and household income data.”

The report added, “The analysis finds that 28 percent of lower-income households in 2010 were located in a majority lower-income census tract, up from 23 percent in 1980, and that 18 percent of upper-income households were located in a majority upper-income census tract, up from 9 percent in 1980.”

As Richard Florida wrote in The Atlantic last month, “The poor face higher levels of segregation in larger, denser metros.” In affluent cities, he said, “The segregation of poverty is more pronounced,” adding, “The poor also face greater levels of segregation in more advanced, knowledge-based metros.”

According to a study published last year in the journal Education and Urban Society, “Students are more racially segregated in schools today than they were in the late 1960s and prior to the enforcement of court-ordered desegregation in school districts across the country.”

In fact, a report last month by researchers at the Civil Rights Project of the University of California, Los Angeles, found, “New York has the most segregated schools in the country.”

Martin Luther King Jr.’s dream about the coming together of children of different races seems, in some ways, to grow more faint.