2020 California Neighborhoods Count: RAND Report

The U.S. Constitution mandates that the federal government count all persons living in the United States every ten years. The census is critical to states because its results are used to reapportion seats in the U.S. House of Representatives; guide redistricting; and form the basis for allocating federal funds, such as those used for schools, health services, child care, highways, and emergency services.In response to long-standing concerns about the accuracy of census data and about a possible undercount, a group of researchers conducted the California Neighborhoods Count (CNC) — the first-ever independent, survey-based enumeration to directly evaluate the accuracy of the U.S. Census Bureau's population totals for a subset of California census blocks.This 2020 research was intended to produce parallel estimates of the 2020 Census population and housing unit totals at the census block level, employing the same items as the census and using enhanced data collection strategies and exploration of imputation methods. Although the CNC was intended to largely replicate census data collection processes, there were a few methodological differences: For example, much of the address canvassing for the 2020 Census was done in-office, whereas the CNC team undertook a complete in-person address-listing operation that included interviews with residents and door-to-door verification of each structure.In this report, the researchers detail their methodology and present the enumeration results. They compare the 2020 Census counts with the CNC estimates, describe limitations of their data collection effort, and offer considerations for future data collection.