Estimates and Implications of the U.S. Census Undercount of the Native-Born Population

Janna Johnson, NORC at the University of Chicago

Awareness of the extent and patterns of error in U.S. Census counts of population (commonly referred to as “undercount") not only has important implications for policymakers and Census enumerators, but also for researchers using the data. While the Census Bureau provides estimates of census undercount for the population using various methods, this paper focuses on calculating the undercount for the native-born using the technique of demographic analysis, which estimates population using information on births, deaths, and migration. Restricting analysis to this population allows for greater reliance on the more accurate birth and death records and less on unreliable migration measures. I estimate undercount using individual-level birth and death records from for those born in 1968 and onward. I find a larger undercount of the native-born population than Census finds for the entire population. I then show this undercount varies widely by characteristics like state of birth and mother’s education.