The working paper says that Black-owned homes are being assessed at higher values than their actual sales price. Economists analyzed more than a decade of tax assessments and sales data of 118 million homes nationwide. In nearly every state, researchers found that property tax assessments were higher in areas with more Black as well as Hispanic residents.

Inequities in tax assessment have been built into the system for decades and have continued, researchers note. “During the Jim Crow era, local white officials routinely manipulated property tax assessments to overburden and punish black populations and as a hidden tax break to landowning white gentry,” University of Virginia historian Andrew Kahrl told The Washington Post. Some county assessors intentionally overvalued black properties back then, says Kahrl, who has researched the history of property discrimination against Black Americans.

The value of Black-owned homes tends to be more moderate than the value of White-owned homes. But if assessors assume a Black-owned home increases value at the same pace as White-owned homes, the assessed value can then outpace the market. The Black family then tends to pay more in property taxes, even though their home value isn’t increasing as quickly.

The economists also reviewed 3.4 million property tax appeals from Chicago and the surrounding area. They found Black homeowners were significantly less likely to appeal their property tax assessments. For those who did, they were less likely to win. The researchers note that national appeals data is unavailable and that Cook County is just one snapshot, but could represent a broader issue nationwide too.

The study is not designed to show “active” discrimination, Howard told The Washington Post, but it can’t be ruled out either. “You can equally tell the story that assessors don’t realize how unequally the burden is landing along racial and ethnic lines,” Howard says.