A couple of weeks ago, I mentioned a jarring pair of demographic facts about public schools in America: Their enrollment is growing more diverse than ever — this fall marks the first school year where minorities now make up the majority of students — yet black and Hispanic students often remain segregated at historic levels. The country is growing more diverse, but schools are not. Nationwide public school enrollment is growing more diverse, but classrooms are not.

This is a national pattern, but children attend school within a much more local context. And now the Urban Institute has created a useful set of county-level maps of public-school segregation drawn from the Department of Education's National Center for Education Statistics that helps make this clear. "There’s a national truth that’s important to recognize," says Margery Austin Turner, a senior vice president at the Urban Institute. "But to really understand what’s going on it, it’s not one national story. It's a bunch of metropolitan and local-level stories."

All of these maps aggregate primary and secondary public-school enrollment up to the county level (some counties are synonymous with a single school district, while others contain many). This first map shows where white children predominantly attend majority-white schools:

This map shows, in darker colors, the counties where black children attend schools where most of their classmates are also minorities:

And this last map shows a similar picture for Hispanic public-school children:

A couple of patterns immediately stand out, but it's important to distinguish what's driving them. Large portions of the West, the Great Plains and the Midwest appear on these maps as if they're doing a great job integrating minority students. But that's largely because there are few minorities living there. Conversely, it appears in these same places as if nearly all white children are attending majority-white schools. But that's due to their underlying demographics as well.

What's more revealing is to look at the places with large minority populations. In the District of Columbia, for instance, just 8 percent of public-school students are white. Yet more than a third of them (37 percent) are clustered within the smaller number of schools where a majority of their classmates are also white. Montgomery County, Md. is relatively diverse, with 34 percent of students white, 21 percent black and 26 percent Latino. But nearly 90 percent of both black and Hispanic children attend majority non-white schools. These children, in other words, live in a diverse county, but they don't attend diverse schools.

In Arlington, Va. blacks make up 11 percent of public-school students in the county. But 81 percent of those black children go to majority non-white schools.

Los Angeles (14 percent), Philadelphia (15 percent) and Essex County, N.J., around Newark (28 percent) all have relatively small white populations in their public schools. And yet a disproportionately high number of those white students attend a small number of majority-white schools (41, 44, and 72 percent, respectively).

In sum: Many extremely diverse regions still have majority-white schools. And many cities with relatively few minorities still funnel them into a small number of majority non-white schools. This pattern — often driven by housing segregation — explains how a county or school district might be diverse even when the educational experience of its children is not. It also explains how it's possible that regions might have increasing diversity in their populations, even as they have decreasing diversity in their schools.

This analysis, however, leaves unspoken an important aspect of what segregation means for how and with whom children learn.

"One thing that this map doesn’t show is that there are two forms of segregation going on: one is by race and the other is by income," says Reed Jordan, a research assistant at Urban. "It really isn’t just that black students attend schools where most of the other children are of color. It’s that black students attend schools where most of the other children of color are poor."

All of this, meanwhile, is creating a disconnect between the environments where children learn, and the world we expect them to grow into.

"This isn’t just a feel-good issue or 'gee what are we doing wrong with respect to minority kids?'" Turner says. "Our country is becoming majority-minority. We all need to know how to talk to each other and work with each other, and appreciate each others' perspectives. If we’re not giving our kids the opportunity to learn that when they’re young and open-minded, it’s not good for our whole country’s future."