In the technical documentation provided here, that originally comes from the Census: https://assets.nhgis.org/original-data/gis/TGRSHP2020_TechDoc.pdf
It describes the 2010 definition of urban areas and not the 2020 definition that did not differentiate between urban clusters and urban areas.
Is that an error in the technical documentation or what am I missing?
In short, the 2020 TIGER/Line Technical Documentation is outdated. That document has an issue date of February 2021. At that time, the Bureau had not yet defined the 2020 urban areas. The original 2020 TIGER/Line files included an urban area layer but only for 2010 urban areas. The Bureau added a layer for 2020 urban areas to the 2020 TIGER/Line files in early 2023. (“Released January 6, 2023,” according to text on the 2020 TIGER/Line page today.) But I haven’t been able to find any updated 2020 Technical Documentation–only this February 2021 version that describes only the 2010 urban areas.
Some related notes:
- The other document you shared is accurate, but your wording is not exact: the 2020 urban area definitions do not differentiate between urban clusters and urbanized areas. (Your wording was “urban clusters and urban areas”.) As I recall, one of the motivations for ending this distinction is the frequency with which people have confused “urban areas” and “urbanized areas.” That won’t be a problem with the new definitions!
- The 2020 TIGER/Line files generally provide separate layers for 2010 and 2020 vintages of all levels of census geography–e.g., 2010 and 2020 census tracts–but at the time of the original 2020 TIGER/Line release, it included the 2020-vintage layers only for levels that had been defined, and 2020 urban areas had not been.
- The 2020 & 2021 releases of American Community Survey summary files use 2010 urban area definitions and not 2020 urban areas, so to map data for urban areas from those ACS releases, you’d need a 2010 urban area layer, which the 2020 & 2021 TIGER/Line files provide.
- When we added NHGIS boundary files based on the 2020 TIGER/Line files, we added the 2010 urban area layer, but our name & description for the file gives no indication that it represents 2010 urban areas. It (problematically) appears to be a 2020 file like our other 2020 boundary files. As it happens, I was already planning to work on this exact issue today! I’ll be creating a new NHGIS boundary file for the actual 2020 urban areas from the 2020 TIGER/Line, and I’ll adjust the name & description of the existing NHGIS “2020 urban areas” file to clarify that it represents 2010 urban areas. We’ll release these updates soon along with tables from the 2020 Census DHC (Demographic & Housing Characteristics) file.