School district borders often divide students by income — and in Detroit and many other places across the U.S., that gulf is especially wide.

That is the conclusion reached in a report released Tuesday by EdBuild, a nonprofit dedicated to overhauling the way states fund education. The report looked at neighboring school systems and found that the poverty rate can be eight times higher from one district to the next.

“You’re talking about, really, haves and have-nots that are living across an imaginary border that has become very important and has become impermeable,” said Rebecca Sibilia, founder and CEO of EdBuild.

With education budgets funded largely by property taxes, poorer school districts can’t pull in as much money as their better-off neighbors — even taking into account federal aid for poor students. Meanwhile, students who live in poverty often need more resources to succeed in school.

The starkest dividing line in the country separates Detroit from neighboring Grosse Pointe Schools, according to the report. In Detroit, 49 percent of children live in poverty, while the poverty rate in Grosse Pointe is only 7 percent. (Other recent measures of child poverty put Detroit’s rate even higher.)

The disparity is deeply rooted. In the 1970s, black parents and the Detroit NAACP sued over racial segregation in the city’s schools. In Milliken v. Bradley, the U.S. Supreme Court ruled that neighboring school districts could not be forced to participate in integration plans. Today, the income disparity between Detroit and Grosse Pointe is even greater than at the time of the court decision, according to EdBuild’s report.

“It is sadly ironic that the number one border remains the border that was decided in Milliken,” Sibilia said.

Separating students by income can have damaging effects in the classroom, said Halley Potter, a fellow at The Century Foundation, a think tank that focuses on inequality, among other issues.

“When you have concentrated poverty you tend to see the weakest outcomes for low-income students,” she said. “Students are missing out on some of those chances to learn from different exposures, different experiences than they’ve had.”

The neighboring school districts with the widest disparity in poverty rates:

Michigan: Detroit City School District (49.2 percent) and Grosse Pointe Public Schools (6.5 percent)

Alabama: Birmingham City School District (48.5 percent) and Vestavia Hills City School District (6.2 percent)

Alabama: Birmingham City School District (48.5 percent) and Mountain Brook City School District (7 percent)

Pennsylvania: Clairton City School District (48 percent) and West Jefferson Hills School District (7 percent)

Ohio: Dayton City School District (47.2 percent) and Beavercreek City School District (6.58 percent)

Arizona: Balsz Elementary District (51 percent) and Scottsdale Unified District (11 percent)

Ohio: Dayton City School District (47.2 percent) and Oakwood City School District (6.96 percent)

Ohio: Youngstown City School District (46 percent) and Poland Local School District (7 percent)

Colorado: Sheridan School District 2 (49 percent) and Littleton School District 6 (9 percent)

Illinois: Carbon Cliff Barstow School District (45 percent) and Geneseo Community Unit School District 228 (6 percent)

Chalkbeat is a nonprofit news site covering educational change in public schools.