This map from the DC Policy Center shows what an overwhelming amount of the District's housing stock is comprised of single-family homes. Most of the housing outside of downtown DC consists of low-density buildings, illustrated above in purple, its new report "Taking Stock of the District’s Housing Stock" shows.
The DC Policy Center estimates that about 303,950 housing units are available to District residents. Of these, 93,470 are single-family homes that make up 30% of the housing stock but a whopping 80% of the residential buildings. The remaining 23,900 buildings hold about 120,600 rental apartment units, 64,300 condominiums, and 28,600 co-op units.
"The footprint of small, single, or double unit buildings in the District is extremely large, giving certain parts of the city a suburban feeling," an article about the report says. "For a land-constrained city, the District has set aside a significant amount of land for low-rise, low occupancy housing units."
So why does that matter? DC and the region as a whole are experiencing a housing shortage, which is driving up the cost of rent. The Metropolitan Washington Council of Governments (COG) says the region needs 115,000 additional homes above current projections by 2045, or about 25,600 total new units per year, to meet residents' need.
Because of the way the city is zoned, there's a lot of space reserved for single-family homes and fewer places to build taller and denser housing types that more people can afford. That also means that neighborhood change can only happen easily in certain areas of the city.