This open access book describes the differences in US census coverage, also referred to as “differential undercount”, by showing which groups have the highest net undercounts and which groups have the greatest undercount differentials, and discusses why such undercounts occur. In addition to focusing on measuring census coverage for several demographic characteristics, including age, gender, race, Hispanic origin status, and tenure, it also considers several of the main hard-to-count populations, such as immigrants, the homeless, the LBGT community, children in foster care, and the disabled. However, given the dearth of accurate undercount data for these groups, they are covered less comprehensively than those demographic groups for which there is reliable undercount data from the Census Bureau. This book is of interest to demographers, statisticians, survey methodologists, and all those interested in census coverage.

The decennial Census is the US Government's largest statistical undertaking, and it costs billions of dollars in planning, execution, and analysis. From a statistical viewpoint, it is critical because it is the only database that maps every inhabitant into a geographic location. By constitutional mandate, census data are the basis for reapportioning the House of Representatives and the Electoral College. The states use census data to redistrict their state legislatures and often to redraw boundaries for local elections. Census data inform the distribution of over $1.5 trillion in federal funding during the decade. This book details the fundamentals and significance of the 2020 Census for the non-specialist reader. It covers why the Census is the only statistical activity required by the US Constitution, the challenges of working towards an accurate and complete count, and what political ramifications flow from this process. Concise, timely, and comprehensible, this book provides helpful real-life examples while also offering an overview of the entwined statistical and political issues that surround the Census.