The Census Bureau measures demographic, social, and economic characteristics of the United States population and housing through the American Community Survey (ACS). Coverage is the measure of completeness of the estimates of housing units (HU), persons living within HUs, and group quarters (GQ). Undercoverage exists when HUs, GQs, or people do not have a chance of being selected in the sample. Overcoverage exists when HUs, GQs, or people have more than one chance of selection in the sample, or are included in the sample when they should not have been. The Census Bureau produces ACS coverage rates for the nation and states every year based on comparisons of the ACS estimates before controls to the Census Bureau’s Population Estimates Program (PEP) estimates (U.S. Census Bureau, 2012a). However, a comprehensive and exhaustive analysis of the coverage of the ACS data has not been undertaken since 1999(Shapiro and Waksberg, 1999), before the full implementation of the ACS. A more current and thorough study of ACS coverage rates may help the Census Bureau focus its resources better by identifying areas that may warrant special efforts.

In this report we estimated ACS coverage by comparing the ACS estimates before controls to the2010 Census counts. The 2010 Census offered a unique opportunity to measure the coverage of the recently produced 2010 ACS 1-year and 2006-2010 ACS 5-year estimates, as it provided an up-to-date listing of housing units and population for comparison. Previous published measures of the ACS coverage were based on comparisons to the PEP estimates, which were themselves based on the Census 2000 and not as up to date. Furthermore, comparing to the 2010 Census counts allowed for detailed estimates of coverage of small geographies or race/ethnic groups not afforded by comparisons to the PEP.

An earlier report appeared on the coverage of the American Indian/Alaska Native (AIAN) persons and of people living in AIAN1 areas. This earlier report used essentially the same methodology as the current report and its results are included here. The current report examines person coverage of basic demographics groups, housing unit coverage, and coverage for the national, state, and tract-level geographies. It also includes a separate analysis of the coverage of HUs and persons in the Puerto Rico Community Survey (PRCS).