Blue dots appear on an interactive map of Minneapolis, representing property deeds with language prohibiting black people from buying homes in certain neighborhoods. As the time-lapse image fast-forwards from 1910 to 1960, the dots become splashes of color that engulf entire sections of the city.

The map is the product of Mapping Prejudice, a project at the U’s John R. Borchert Map Library. Supported in part by private gifts, it is the first-ever effort to comprehensively map the use of racially restrictive covenants in a U.S. city.

Researchers from the U and Augsburg University, along with nearly 800 volunteers, spent the past two years examining Hennepin County property deeds, then mapping the location of those containing restrictive language

“By 1940, Minneapolis was extremely segregated,” says project manager and U of M librarian Ryan Mattke, ’04 B.A., ’15 M.G.I.S.

So far, the team has identified more than 6,000 deeds with racial restrictions in Minneapolis. Although the use of such covenants was declared illegal in 1968, the language is still buried in many property deeds.

Mattke says people are often surprised to learn of the practice and how the effects are still seen in some neighborhoods. “To be able to unearth the actual primary documents, show people the deed, and map it is powerful,” he says.