Since its inception in January 2014, Mapping Segregation in Washington DC has focused primarily but not exclusively on racially restricted housing in the Northwest quadrant of the city east of Rock Creek Park. We 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 launched.
Lots restricted by deed are those for which the seller, generally a real estate developer, included a racial covenant in the property deed. For covenants found on properties developed prior to 1921, we checked the building permits and mapped all the properties included in the same permit, provided that we could document a covenant for at least at least one in ten lots per permit. In some cases, we also counted lots as restricted if others in the same subdivision, being sold by the same owner, were found to have covenants. For these lots, the subdivision name is listed in the popup. Current addresses were generated based on the boundaries of each historic lot that had a covenant. In some cases, the historic lots do not match today's lots.
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. 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 Minnesota Population Center’s National Historic Geographic Information System and the U.S. Census Bureau. Categories of information published by the Census vary from decade to decade; for example, it sorted households by white and nonwhite for 1950 and 1960 but by white and black for 1970. We have therefore calculated the figures for nonwhite households to make decade-to-decade comparisons more accurate. The Census defines housing with more than one person per room as "crowded," and with more than 1.5 persons per room as "severely crowded." Within each decennial dataset, data is missing for some blocks. The data and shapefiles are downloadable here. Humanities DC funded digitization and mapping of the Census block data.