Median Year Built
The vintage of a tract's housing stock, as the median year its structures were built and the share standing since before 1960.
How old the housing in a tract is.
The Census Bureau defines year structure built as "when the building was first constructed, not when it was remodeled, added to, or converted." For mobile homes, houseboats and recreational vehicles, "the manufacturer's model year was assumed to be the year built." The data "relate to the number of units built during the specified periods that were still in existence at the time of interview." The median "divides the distribution into two equal parts: one-half of the cases falling below the median year structure built and one-half above the median," and is "rounded to the nearest calendar year" (ACS Subject Definitions).
The question is asked at both occupied and vacant housing units, so the measure describes the standing stock rather than only the inhabited part of it.
Housing age carries information that is hard to get elsewhere. It stands in for construction era and building code, for lot pattern and street layout, and for the maintenance and retrofit costs an owner is likely to face.
Metrics in this family#
Median year built
levelThe median construction year of housing structures in the tract, as a calendar year.
Considerations#
Only surviving buildings are counted. Units demolished before the survey are absent, so an area that has replaced much of its old stock reads as newer than its development history would suggest. Conversely, a substantially rebuilt or gut-renovated building keeps its original construction year.
Year built is reported by the occupant or owner rather than taken from permit records, and recall of a construction date is imperfect for older buildings.
The Bureau computes the median across published construction-period bands rather than from exact years, so it is an interpolated figure.
ACS 5-year windows overlap. Each vintage shares four of its five years with the vintage before it, so movement between adjacent vintages reflects smoothed rolling estimates rather than independent annual readings. Housing stock also turns over slowly, and these measures move very little from one vintage to the next.
Census tract boundaries were redrawn for the 2020 census. Estimates published on earlier boundaries are carried onto current ones before use — see geography.
In tracts with few housing units the estimate rests on a small sample and carries a wide margin of error.
References#
- 1ACS Subject Definitionshttps://www2.census.gov/programs-surveys/acs/tech_docs/subject_definitions/2024_ACSSubjectDefinitions.pdf