Fundamental questions about the size and characteristics of the homeless population are unresolved because it is unclear whether existing data are sufficiently complete and reliable. We examine these questions and the coverage of new microdata sources that are designed to be nationally representative. We compare two restricted data sources largely unused to study homelessness, the 2010 Census and American Community Survey (ACS), to restricted Homeless Management Information System (HMIS) data, HUD's public-use point-in-time (PIT) estimates, and the Housing Inventory Count (HIC) at the national and individual level. We also develop a new approach to estimating the size of the sheltered homeless population using linked Census and HMIS microdata. Our analyses suggest that on a given night there are about 400,000 people experiencing homelessness in shelters in the U.S. and about 200,000 people sleeping on the streets, with this latter estimate subject to greater uncertainty. More than 90 percent of those in shelters appear to be counted in the Census, although many are classified as housed or in other group quarters, due largely to ambiguity in the definition of a homeless shelter. This paper lays the foundation for pathbreaking future work with these data on the U.S. homeless population.

关于无家可归人口的规模和特征的基本问题尚未解决，因为尚不清楚现有数据是否足够完整和可靠。我们研究了这些问题以及旨在具有全国代表性的新微数据源的覆盖范围。我们将两个主要未用于研究无家可归者的受限数据源（2010 年人口普查和美国社区调查 (ACS)）与受限的无家可归者管理信息系统 (HMIS) 数据、HUD 的公共使用时间点 (PIT) 估计以及国家和个人层面的住房库存计数 (HIC)。我们还开发了一种新方法，使用关联的人口普查和 HMIS 微数据来估算受庇护的无家可归人口的规模。我们的分析表明，在某个特定的夜晚，大约有 400 个，美国有 000 人在收容所中无家可归，约有 200,000 人露宿街头，后者的估计存在更大的不确定性。超过 90% 住在收容所的人似乎都计入了人口普查，尽管许多人被归类为有住房或其他集体宿舍，这主要是由于流浪者收容所的定义含糊不清。本文为利用这些关于美国无家可归人口的数据开展开创性的未来工作奠定了基础。