State of Illinois Census & Data Collaboration

PGHNP1 Abraham Lincoln statue in front of the Illinois State Capital Building in Springfield, Illinois

Problem

The State of Illinois wants to ensure its population counts and estimates are accurate.

To make sure that the 2020 Census counts are accurate, the US Census Bureau runs programs that allow states, counties, and cities to submit for review data showing their populations may have been enumerated incorrectly or missed. The Population Estimates Program (PEP) releases updated estimates each year following the decennial census. The Post Census Group Quarters Review Program challenge program ran in 2023 only. The State of Illinois experienced significant environmental challenges to enumeration during the 2020 Census, including the COVID-19 pandemic and unrest related to protests. The State wants to make sure that the enumeration of their population is as accurate as possible given these events.

Solution

NORC’s expertise with administrative records helps the State of Illinois ensure an accurate population count.

In preparation for the State of Illinois's response to the Post-Census Group Quarters Review challenge program, the NORC team acquired, cleaned, harmonized, and geocoded information about facilities in the State that met Census Bureau definitions of group quarters (such as nursing homes, dorms, and residential treatment centers). Methodological experts created a frame and identified gaps between it and Census records. A vetting team verified facilities that potentially had been undercounted.

For the Population Estimates challenge program, NORC methodologists are evaluating the Census Bureau methodology for producing its annual estimates of the Illinois population. Using multiple sources of administrative data, NORC is developing alternative methods to estimate the State’s population and will recommend the best method for the State. In addition, through this partnership, NORC’s demographic, statistical, and data science experts are providing ongoing technical consultation to the State as it prepares for the 2030 Census. Early planning activities may include enhancement of the methodology used for population estimation, establishment of a master housing unit database, data harmonization, and dissemination.

Result

An accurate population count advances the State of Illinois’s equity efforts.

NORC identified 733 group quarters facilities that may have been missed during the 2020 decennial census, representing over 46,000 Illinois residents. The Census Bureau will add these people to future annual population estimates. Accuracy of population counts and estimates is imperative because the State relies on census data at every level of planning and policy-making. The project is also directly aligned with the State’s efforts to advance equity in how it provides services and resources to residents.