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United States

In the United States, in the early 20th century zoning laws were used to prevent integrating neighborhoods but were struck down in Buchanan v. Warley. Thus, deed restrictions and restrictive covenants became an important instrument for enforcing racial segregation in most towns and cities, becoming widespread in the 1920s and proliferating until they were declared unenforceable in 1948 in the Supreme Court case Shelley v. Kraemer. They prohibited a buyer of real property from allowing use or occupancy by members of a given race, ethnicity, or religion as specified in the title deed. Such covenants were employed by many real estate developers to "protect" entire subdivisions, with the primary intent to keep " white " neighborhoods "white". Ninety percent of the housing projects built in the years following World War II were racially restricted by such covenants. Cities known for their widespread use of racial covenants include Chicago, Baltimore, Detroit, Milwaukee, Los Angeles, Seattle, and St. Louis.