All,

 

Thank you to all who submitted comments seeking to update the rules for block group and census tract delineation for the 2020 Census Participant Statistical Areas Program (PSAP). The transportation planning community’s submissions were substantial and the Census Bureau is interested in finding a solution to our needs while working within their own limits to ensure standards for survey data quality and privacy concerns.

 

The Census Bureau has distilled comments relating to combining residence-based and workplace-based delineations into three options and has asked us to give feedback on how workable these options may be. Two of them seem more plausible for the Census Bureau’s final ruling on 2020 PSAP criteria, but may be more limiting than transportation planners would desire. We are seeking people willing to test out these options with their own geographies. We’d like to know whether one option is more workable or preferable than the others--and why. Do some options work better for single-use geographies but not as well for mixed-use? Do they work better or worse than how your TAZs are currently delineated?

 

We will use this survey form (https://goo.gl/forms/SgHrqne2NhGjUsEr2) to collect comments about folks’ observations when testing the options. Time is limited, as the Census Bureau has only this summer to finalize how PSAP 2020 will work. If you’re willing to test one or more of these options in a sampling of your communities and workplaces, we must receive your feedback by June 20. If you’d like to view others’ comments before or after submitting your own, scroll to the bottom (leaving the form blank) and press submit. You will have the opportunity to see your own answers after submitting and to revise your response, if desired.

 

One of the key differences--highlighted in the options below--between the needs of the ACS and the CTPP special tabulation is that the ACS does not report workplace geography below county subdivision or census designated place. CTPP will continue to seek workplace and journey-to-work flows by tract--and in post 2020 releases--block group. It may be desirable for CTPP data quality to see workplace-based geographies with employment counts high enough to get a reasonable samples of workers at smaller geographies, but the Census Bureau has no need for ACS reporting to see block groups meet a minimum threshold of employment--especially when it comes from a local source they have no way of verifying. In other words, the CTPP Oversight Board’s recommended comments of a minimum threshold for employment for block groups and tracts (on par with population minimum thresholds for those geographies) may be good practice for delineating to get better workplace data in the CTPP, but may not be necessary from the Census Bureau’s perspective.

 

Please try these criteria for delineation on your current geography and add your comments to the google sheet

 

Option A: Employment thresholds where population or housing is not present

This scenario gives priority to population or housing units for delineating standard block groups (min: 600 people or 240 housing units; max: 3000 people or 1200 housing units) and tracts (min: 1200 people or 480 housing units; max: 8000 people or 3200 housing units). If an area was devoid of population or housing, that area could be delineated by a minimum threshold of 600 employees per block group and 1200 per tract. Special Use block groups and tract criteria would stay the same (Within an urban area: min. 1 square mile; Outside an urban area: min. 10 square miles).

 

Option B: Only need one threshold met--population, housing or employment

This scenario allows for some presence of population or housing that may or may not meet a minimum threshold, as long as it meets an employment minimum of 600 jobs in block groups or 1200 in tracts. Conversely, it allows for population of 600-3000 in block groups or 1200-8000 in tracts without meeting a 600 or 1200 job threshold, respectively. Special Use block groups and tract criteria would stay the same. This is seen as a very unlikely option from the Census point of view because it would degrade resident sample sizes to a point where disclosure would be a real concern.

 

Option C: Special use block groups and tracts have no minimum area criteria - no employment thresholds

Rather than seeking employment thresholds, removing the square mileage criteria of the special use block groups and special use tracts would allow agencies to define non-residential land in whatever way they want. If there is no presence of population or housing units, non-residential land-uses could be carved up by block group and tract boundary rules (see below info on boundary rules below). Those concerned with achieving a minimum sample size of workers at workplace may opt to consider employment counts while delineating, but would not need to report this as justification for where proposed tract and block group boundaries are delineated. Residential areas would follow current standard block and standard tract population/housing unit thresholds.

 

What PSAP guidance says on boundary line features:

For tracts, beyond using governmental (County, reservation or MCD [where applicable]), or “permanent natural and constructed features, such as roads, shorelines, rivers, perennial streams and canals, railroad tracks, or above-ground high-tension power lines”, the federal register allows: “boundaries of large parks, forests, airports, penitentiaries/prisons, and/or military installations, provided the boundaries are clearly marked or easily recognized in the field in imagery and on the ground.” Barring all that, it says: “When acceptable visible and governmental boundary features are not available for use as census tract boundaries, the Census Bureau may, at its discretion, approve other nonstandard visible features, such as major ridgelines, above-ground pipelines, intermittent streams, or fence lines. The Census Bureau may also accept, on a case-by-case basis, relatively short stretches of boundaries of selected nonstandard and potentially nonvisible features, such as cadastral and parcel boundaries or the straight-line extensions or other lines-of-sight between acceptable visible features.” More details here: https://www.federalregister.gov/documents/2018/02/15/2018-02625/census-tracts-for-the-2020-census-proposed-criteria

 

For block groups, the same can be said, with the addition that any block group “nest” within its “parent” census tract. More details here: https://www.federalregister.gov/documents/2018/02/15/2018-02624/block-groups-for-the-2020-census-proposed-criteria 

We've very appreciative of any feedback you can give on this important matter. Thank you in advance!    

Ben Gruswitz, AICP | Senior Planner
Office of Long-Range Planning
Delaware Valley Regional Planning Commission  
190 N Independence Mall West, 8th Floor
Philadelphia, PA 19106-1520
215.238.2882 | bgruswitz@dvrpc.org   

www.dvrpc.org