Earlier this year, the Southern Education Foundation reported that America's public schools had reached a dispiriting milestone: A majority of children attending them are now low-income. As The Post's Lyndsey Layton noted at the time, we haven't seen such demographics in public schools at any point over the past half-century. And they mean that teachers must increasingly prioritize combating the effects of poverty — ensuring children feel safe, fed and well-clothed — before the learning even begins.

This picture of poverty in the classroom, however, varies widely across the country, between North and South, and between urban counties and nearby suburban ones. The Urban Institute on Wednesday released interactive maps showing that the concentration of poor children in public schools is remarkably high in some of these places relative to others — and that these geographic disparities are magnified for children of color.

The above map shows the share of children in public schools in each county who come from low-income families (low-income is defined here as households making at or below 185 percent of the federal poverty line, the cutoff for free and reduced-price lunch programs). Particularly striking is the "belt of rural poverty" across the South, as the Urban Institute puts it.

The share of low-income children is also high in several metropolitan areas: in Dallas County (73 percent), in Cook County around Chicago (66 percent), in the District of Columbia (61 percent). In several Lakota counties in South Dakota, the number of public school children who come from low-income families approaches 100 percent.

This concentration of poverty, which reflects underlying patterns in where the rich and poor live, also means that a poor child in America is much more likely than a middle-class or wealthier child to attend a high-poverty school. About 40 percent of low-income children attend public schools where 75 percent of the other students are low-income, too. The same is true of just 6 percent of non-poor kids.

"This is concentrated disadvantage," writes Urban Institute researcher Reed Jordan, "the children who need the most are concentrated in schools least likely to have the resources to meet those needs."

Across the country, black children are also about six times more likely to attend high-poverty schools than white children. In many counties in the rural South, nearly all of the black children attend high-poverty schools:

Urban Institute

Disparities in the level of school poverty that white and black children experience often vary as well within the same region. Jordan again:

In some metropolitan areas, the racial concentration of school poverty is so severe that black and white students effectively attend two different school systems: one for middle- and upper-middle-income white students, and the other for poor students and students of color.

This happens, for example, in Cook County around Chicago. There, 75 percent of black students attend high-poverty schools. For white children, the share is less than 10 percent.

These maps reflect the importance of better integrating schools, creating environments in which poor children learn alongside upper-income peers. But that's a goal that will be hard to achieve if we don't talk as well about the housing patterns and policies that helped create these maps.

You can navigate the full data and interactive maps here.