Census Bureau Estimates Illinois Population, Young Children Undercounted in 2020 Census
The U.S. Census Bureau has released estimated 2020 Census undercount and overcount rates for all 50 states and the District of Columbia, and Illinois is one of six states with a statistically significant population undercount (nearly 2 percent). There were eight states with statistically significant overcounts, and 36 states without an undercount or overcount (see map below).
In addition, young children ages 0 to 4, a "historically undercounted population in decennial censuses," continue to be undercounted in the United States. In fact, the 2020 Census had a larger undercount of young children than every census since 1970.