The Size and Census Coverage of the U.S. Homeless Population

Despite widespread concern about homelessness, fundamental questions about the size and characteristics of this hard to study population are unresolved, in large part because it is unclear whether existing data are sufficiently complete and reliable. We examine these questions as well as the coverage of new microdata sources that are designed to be nationally representative and will allow pathbreaking new analyses. We compare three restricted use data sources that have been largely unused to study homelessness to less detailed public data. In doing this triangulation of sources, we examine the completeness and accuracy of available data and improve our understanding of the size of the homeless population and its inclusion in the Census and household surveys. Specifically, we compare restricted data from the 2010 Census, American Community Survey (ACS), and Homeless Management Information System (HMIS) to HUD's public-use point-in-time (PIT) estimates and the Housing Inventory Count (HIC) at the national, city and county, and person level. We also develop a new approach to estimating the size of the sheltered homeless population using linked Census and HMIS shelter microdata. Our analyses suggest that on a given night there are about 600,000 people experiencing homelessness in the U.S., about one-third of whom are sleeping on the streets and two-thirds in shelters. More than 90 percent of those in shelters were counted in the Census, although many were classified as housed or in other group quarters, a result that stems largely from ambiguity in the definition of a homeless shelter. By establishing the broad coverage and reliability of the new data sources, this paper lays the foundation for pathbreaking future work on the characteristics, income, safety net participation, mortality, migration, geographic distribution, and housing status transitions of the U.S. homeless population.