The 1.5-percent decrease in population reported for Bloomington by the US Census last week has generated local skepticism about the accuracy of the count.
The most recent estimates from the US Census had pegged the city’s population at around 86,000. But the 2020 numbers came in under 80,000, less even than the actual count in 2010.
The result was a big enough surprise that the city’s mayor, John Hamilton, issued a statement last Friday, the day after the results were released. The statement raises the possibility that the reported numbers are not accurate, because of an undercount of Indiana University students.
Hamilton’s statement points out: “[M]uch of the census data collection began the very week thousands of university students were directed to leave for the semester due to the COVID pandemic.”
If an undercount of university students contributed to Bloomington’s lower numbers, the undercount would likely be detectable in the geographic distribution of population losses in Bloomington, as counted by the US Census.
Based on a B Square plot of precinct population counts in 2020 compared to 2010, the idea that college students were undercounted has some statistical support.
It was predominantly areas on and near the Indiana University campus that showed lower counts in 2020 compared to 2010.