23 Aug
2021
23 Aug
'21
1:32 p.m.
The Census Bureau is ramping up efforts for Census 2020 PUMA delineation. PUMAs are
“Public Use Microdata Areas.” They are large, contiguous areas of 100,000+ population,
built up from census tracts and counties.
Here’s the main Census Bureau page on PUMA 2020:
https://www.census.gov/programs-surveys/geography/guidance/geo-areas/pumas/…
<https://www.census.gov/programs-surveys/geography/guidance/geo-areas/pumas/2020pumas.html>
The Census Bureau will be kicking off the program in September 2021 (next month!). This
will be an announcement to each State Data Center points of contact.
If you’re an MPO, you might be part of your state’s State Data Center Network (as an
affiliate data center, regional data center, etc.) Get in touch with your state’s SDC. It
will be each SDC that provides proposed PUMAs to the Census Bureau.
The actual work on defining the new Census 2020 based PUMAs will be November 2021 through
January 2022, with the “final” 2020 PUMAs published by summer 2022.
My key point: the PUMAs are NOT just for use in the Public Use Microdata Sample, but are
used as STANDARD tabulations for the American Community Survey, both the 1-year and 5-year
products. As such, the PUMAs can be thought of as “Regional Analysis Districts” or
“Superdistricts” or “Regional Districts.” They can be SUPER useful in MPO transportation
planning analyses.
Here is the Census Bureau’s statement on the usefulness of PUMAs, from the “Final
Criteria” document:
"In addition to PUMS data publication, as the ACS was developed and implemented after
the 2000
Census, standard PUMAs were adopted as a basic tabulation geographic entity to present
summary
data. This was in response to concerns raised by SDCs and other stakeholders that the
minimum
population thresholds for tabulation and dissemination of 1-year and 3-year ACS data
(65,000 and
20,000 persons, respectively) would limit the availability of data for the predominantly
rural portions of
states as well as for many counties. PUMAs met these population size requirements for all
ACS data
tabulations and their adoption resulted in a substantially larger community of PUMA data
users, many
of whom do not use PUMS files. This sustained interest in PUMA geography and associated
data is
expected to continue, therefore the PUMA criteria and guidelines for the 2020 Census are
intended to
help maintain a stable and comparable dataset.”
[from: Final Criteria for Public Use Microdata Area for the 2020 Census and the American
Community Survey]
Note that the current set of Census 2020 PL 94-171 data files do NOT have PUMAs as a
standard summary level. This is because the Census 2020 includes the 2020 Census Tracts,
and the current PUMAs are based on the 2010 Census Tracts.
My recommendation for MPO staffs. To me this is a GIS-heavy process:
1. Map the Census 2010 Census Tracts and PUMAs.
2. Map the Census 2020 Census Tracts. Ideally the 2020 tracts nest within the 2010 tracts,
but boundaries do indeed change.
3. Develop an equivalency between 2020 Census Tracts and 2010 PUMAs.
4. Use PL 94-171 data to get Census 2020 census tracts, and aggregated to approximate the
2010 PUMAs.
5. If the county is > 200,000 population, consider how to best re-draw PUMA
boundaries.
6. It’s a jigsaw puzzle, where none of the potential PUMAs can be less than 100,000.
Consider this as “redistricting for MPOs"
7. Involve local actors who are interested: counties, cities, academics, nonprofits, etc.
8. Consider the Bureau’s advice on “stable and comparable dataset”… Sometimes you may just
keep the old PUMAs!
Hope this is of interest:
Chuck Purvis, Hayward, California