Analysis of the Census 2020 Count in Detroit
By Patrick Cooney, Ren Farley, Samiul Jubaed, Kurt Metzger, Jeffrey Morenoff, Lisa Neidert, and Ramona Rodriguez-Washington
Each year the Census Bureau releases an official estimate of the residential population of every municipality in the nation. The Census Bureau estimated that in 2019, Detroit had a population of roughly 670,000. However, just one year later, the 2020 Census counted only 639,000 residents living in the city, a decline of roughly 31,000 residents from its 2019 estimate. In the context of the Census Bureau’s previous enumerations and estimates of Detroit’s population, a single-year decline of 31,000 residents is anomalous and implausible. With such a dramatic discrepancy between the 2019 estimates and the 2020 count, it is possible that the Census Bureau either significantly overestimated Detroit’s population in the years preceding 2020 or significantly undercounted the city’s population in 2020.
In this report, we lay out preliminary evidence supporting the latter case, suggesting the Census Bureau undercounted Detroit’s population in 2020. We present the results of an analysis of 10 block groups in Detroit, comparing the Census Bureau’s count of occupied housing units in those block groups with counts from United States Postal Service data from June 2020, when the Census was taking place. For five of these block groups, we also present data from a canvass conducted by Wayne State University (WSU) in September and October 2021 that provides data on the overall number of housing units and the number of occupied housing units in those block groups. Our analysis suggests the 2020 Census produced an undercount of occupied housing units in the 10 sampled block groups, including one set of five block groups with relatively high rates of residential stability and another set of five block groups with higher vacancy rates and lower rates of self-response in the 2020 Census (we refer to these block groups as “less stable”). In the set of more residentially stable block groups we sampled, depending on the data source we use, the 2020 Census appears to have produced an undercount of between 223 and 277 occupied units, counting between 7.6% and 9.5% fewer occupied units. In the five less residentially stable block groups we analyzed, the 2020 Census appears to have produced an undercount of 161 units, or roughly 9% fewer units. In sum, after conducting an audit of the Census counts of residential units and occupied units in a selection of both more stable and less stable Detroit block groups, we find that the 2020 Census appears to have undercounted the number of occupied residential units across these 10 block groups by 8.1%, missing an estimated 964 Detroit residents. If undercounts of a similar magnitude occurred in a majority of the city’s more than 600 block groups, the potential undercount could be in the tens of thousands.
In addition to this block group level analysis, we also analyzed other data produced by the Census Bureau, which show Detroit as an outlier compared to other U.S. cities in the size of the discrepancy between the Census Bureau’s 2019 population estimates and its 2020 population count. Given the circumstances of the 2020 Census count in Detroit (e.g., high reliance on internet self-response and abbreviated Non Response Follow Up (NRFU) period combined with the city’s hard-to-count characteristics) these data offer compelling evidence of a likely undercount of Detroit in the 2020 Census.
- Our data suggest the 2020 Census undercounted the number of occupied residential units in 10 Detroit Census block groups we analyzed by 8.1%.
- Detroit is an outlier compared to other U.S. cities in the extent to which its 2020 Census population and housing counts deviate from the Census Bureau’s 2019 population and housing estimates.
- Data from our analysis of Census block groups and peer cities offer compelling evidence of a likely undercount of Detroit in the 2020 Census.
- Decennial population counts and annual population estimates are critically important, used to determine the allocation of hundreds of billions of dollars in federal funding to state and local governments.
Every year, hundreds of billions of dollars flow to state and local governments based on decennial Census counts and annual estimates. Attaining an accurate count is therefore critically important. This report lays out compelling evidence of a likely undercount in Detroit in the 2020 Census. After reviewing data on the extent to which Detroit was an outlier in the discrepancy between its 2019 population estimate and 2020 count, we engaged in a block group-level analysis to learn more. The magnitude of the potential undercount in these block groups, when combined with the other data we’ve accumulated here, provide sufficient evidence to warrant further investigation, both by researchers and government officials, to ensure the city’s count is accurate.