UCLA Center for Neighborhood Knowledge

This Factsheet summarizes the findings from a comparison of population counts for Los Angeles County from the 2020 data for political redistricting (P.L. 94-171 Redistricting Data or PL94) and the 2015-19 American Community Survey (ACS). The Census Bureau conducts an enumeration of the population every decade and compiles the information to assist local officials to redraw political boundaries in response to population changes to ensure that electoral districts are equal in population size. While the goal for every decennial census is a complete and accurate count, it has never been perfect, both missing some individuals and double counting others.2 One serious problem with miscounting is a differential undercount, where the enumeration systematically undercounts some populations and overcounts other populations. That is, the inaccuracies are not proportionately the same across groups. This problem has profound implications within the redistricting process, essentially disenfranchising those missed by the census and undermining the “one person, one vote” principle. There are also economic consequences because governmental allocation formulas are based on population. Differential undercount is deeply embedded in and shaped by existing structures of inequality. It is, therefore, not surprising that historically low-income persons and people of color are disproportionately missed by the enumeration, thus disproportionately undercounted.