Correction: An earlier version of this editorial incorrectly referred to the General Accountability Office. The correct name of the agency is the Government Accountability Office. This version has been corrected.

On the steps of the Supreme Court in 1954, Nettie Hunt explains the Supreme Court's ruling in Brown v. Board of Education, which struck down segregated public schools, to her daughter, Nickie. (Bettmann/CORBIS)

LAST YEAR, Rep. Paul A. Gosar, an Arizona Republican, explained why he disliked an Obama administration plan to build affordable housing — as a means of helping minorities and poor people — in mainly white, middle-class neighborhoods.

“Instead of living with neighbors you like and choose, this breaks up the core fabric of how we start to look at communities,” Mr. Gosar told the Hill newspaper. “That just brings unease to everyone in that area.”

Yes: “Unease” at the prospect of neighborhood integration has long been central to U.S. racism, or a euphemism for it. It has also played a central role in an equally poisonous problem — the resegregation of public schools — that started accelerating 15 years ago, about a half-century after the Supreme Court ruled that segregated schools are “inherently unequal.”

New data compiled by the Government Accountability Office, Congress’s watchdog, show that the number of high-poverty public schools serving primarily black and Hispanic students nationwide more than doubled, to some 15,000, between the turn of the century and 2014. A bout 16 percent of K-12 public schools now serve predominantly poor, minority students, which also means their students are more likely to lack access to math, science and advanced-level classes and to face higher rates of suspensions, expulsions and other harsh discipline.

Put another way, 62 years after the Supreme Court acted to end segregation in public education, U.S. schools in the 21st century are rapidly resegregating — a function of widening disparities in wealth, entrenched housing patterns and policies, and disparate allocations of funding by government at all levels.

The fault is widely shared. The Supreme Court bears a measure of blame for a 1973 ruling allowing schools to rely primarily on local property taxes for funding. That decision enshrined a system in which Zip codes determine funding levels, saddling poor neighborhoods with resource-starved schools burdened with overcrowded classes and underpaid teachers. The federal government, which provides public schools with less than 10 percent of their funding, is ill-equipped to compensate, and many states make little effort to even out disparities. Sharply increased funding is not an adequate answer, but without it poor schools will be unable to attract the talented teachers they need.

Chipping away at a problem as multidimensional as school resegregation demands a kitchen-sink approach. Policymakers and lawmakers must act forcefully to halt and reverse a corrosive trend that will further balkanize an already-fractured and fragmented society.

The GAO report urged the federal Education Department to intensify its monitoring of school disparities and the Justice Department to take a more aggressive stance to follow up on scores of school desegregation cases, many of them involving court orders issued decades ago.

A critical challenge is the related and underlying problem of community sorting and segregation — including the white neighborhoods Mr. Gosar would insulate from “unease,” and from which spring racially exclusive schools. Mindful of decades of federal policy and private practice that promoted racially concentrated urban and suburban neighborhoods, the Obama administration has advanced policies that would use federal grants as incentives to build affordable housing in relatively affluent areas. That’s a promising start to encourage neighborhood integration, which is so tightly tied to integrating schools.