Estimates of the Naturalized Citizen Population: Comparisons between the ACS and Administrative Records

Bryan Baker, U.S. Department of Homeland Security (DHS)

Becoming a naturalized United States citizen is a measure of assimilation, but estimates of the number of naturalized citizens living in the United States may differ depending on the source. In particular, estimates from the U.S. Census Bureau’s American Community Survey tend to be substantially higher than estimates derived from decades of U.S. Citizenship and Immigration Services administrative flow data. The estimates from the two sources differ by more than is reasonable based on sampling error alone. The purpose of this study is to examine the compatibility of the two sets of estimates and to facilitate improvements in the accuracy and reliability of future estimates by identifying demographic subgroups with disproportionately large differences and identifying and assessing plausible explanations for those differences. General classes of explanations include model error, data collection and data management practices for administrative records, survey question specificity or ambiguity, and respondent reporting error.