(CNN) - Predominantly white school districts in the US get $23 billion a year more than districts that educate mostly non-white children, an education advocacy group says.
A report from EdBuild, which promotes equity in public schools, found that the average white school district got $13,908 for every student in 2016, compared to $11,682 per student in districts that mostly serve people of color.
The country has about 13,000 traditional public school systems, averaging 3,500 students each, the report says. The report defines "white" or "non-white" districts as "racially concentrated" districts -- attended by more than half of US students -- in which the population is either three-quarters white or three-quarters non-white.
The money gap -- a difference of roughly $2,226 per student -- originates in the way Americans pay for education, with locally run schools being tied to local control of taxes.
"We need to take a different approach," EdBuild CEO Rebecca Sibilia told CNN, suggesting that local governments reconsider how school districts are drawn.
White communities tend to have more money to spend on schools. And white school districts tend to be much smaller than non-white school districts, the EdBuild says.
"Small districts can have the effect of concentrating resources and amplifying political power," the report says. "Because schools rely heavily on local taxes, drawing borders around small, wealthy communities benefits the few at the detriment of the many."
The report also found that white districts enroll just over 1,500 students — half the size of the national average -- while non-white districts serve over 10,000 students, about three times more than that average.
The report says 27% of students are in mostly non-white districts and 26% are in mostly white.
The biggest funding gap between the districts was in Arizona, where students in non-white districts received an average of $7,613 less each.
This inequity in Arizona is a "real problem" and a "chief concern" of the state's newly elected Superintendent of Public Instruction Kathy Hoffman, said public information officer Stefan Swiat of the Arizona Department of Education.
"This harkens back to an Arizona of the past that still exists today and we need to eradicate in the future," Swiat said.
Sibilia called the disparity a vestige of America's segregationist past.
"Where people live matters in terms of how well-funded their schools are," she said.
The study considered local and state funding, the main income sources for schools. Federal money was not included since it is intended chiefly to "fill in the gaps," Sibilia said.