A recent NAHB study shows that the median size of a subdivision in the United States is 25 total acres, and the median number of housing units in a subdivision is 50. The results are based on a survey of development projects currently under way or recently completed, conducted by NAHB’s Economics and Housing Policy Group in May 2016. NAHB conducted a similar survey once before, in 2014. Results were not drastically different, although the median number of housing units in a subdivision was somewhat higher in the earlier survey.
The 2016 survey collected information on whether a subdivision was inside or outside a metro area, and the type of housing built in it: single-family detached, attached (townhomes or apartment buildings) or a mix of the two. The median number of housing units in subdivisions inside metro areas is 50, compared to 46 for development outside of metro areas. The median in mixed housing developments is 314 housing units, compared to a median of 65 in attached-only, and 45 in single-family detached only subdivisions.
The survey also collected data on the acreage in the subdivisions, and how much of it was dedicated to housing. From this, it’s possible to calculate a measure of net residential density. The median net residential density for all subdivisions is 4.0 units per acre. For subdivisions located inside metro areas, the median net residential density is 4.0 units per acre, slightly higher than the 3.8 units per acre for non-metro developments. When looking at the net residential density of subdivisions by type of housing, attached-only subdivisions have the largest median net residential density of 18.8 units per acre, compared to 5.8 units per acre in mixed housing developments, and 3.2 units per acre in single-family detached only.
For more detail, including a profile for each of the five major types of subdivisions, a complete set of tables with more information for each type of subdivision and breakdowns by region and housing units in the development, and a copy of the questionnaire, please consult the full study.