Mapping Segregation in Washington DC launched in January 2014 and thus far has focused primarily but not exclusively on racially restricted housing in the Northwest quadrant of the city east of Rock Creek Park. Researchers had documented racial covenants—which barred the conveyance of property to African Americans—on approximately 11,000 properties as of October 2018, when this website was launched.
Lots restricted by deed are those for which the seller, generally a real estate developer, included a racial covenant in the property deed. Lots were also counted as restricted if others in the same subdivision, being sold by the same owner, were found to have covenants. In the case of subdivisions that were not developed until later, possibly after being re-platted, the project mapped as restricted the present-day lots within the boundaries of those early subdivisions.
Lots restricted by petition are those listed in “Agreements” containing homeowner signatures that were gathered by white neighborhood groups. Upon being filed with the DC Recorder of Deeds, these Agreements became legally binding.
Real estate documents filed after mid-1921 are available in the DC Recorder of Deeds’ publicly accessible database, while those filed earlier remain in their original form, in volumes housed at the DC Archives. For covenants found on properties developed prior to 1921, researchers checked the building permits and mapped all the properties included in the same permit, provided that a covenant could be documented for at least at least one in ten lots per permit. Data on building permits and subdivisions is at HistoryQuest DC. The DC Office of the Surveyor’s online records and Baist real estate maps were also consulted for determining historic subdivision and lot boundaries.
Open Data DC contains shapefiles with the boundaries of all current lots. Demographic data was collected from the U.S. Census Bureau and the Minnesota Population Center’s National Historic Geographic Information System. Demographic data was collected from the Minnesota Population Center’s National Historic Geographic Information System and the U.S. Census Bureau. The Census defines housing with more than 1.5 persons per room as "severely crowded."