Paul Hufe, Ravi Kanbur, Andreas Peichl On a single night in January 2020, over half a million people were estimated to be homeless in the US, including over 200,000 people who slept unsheltered on sidewalks, in public parks, and other places not intended for human habitation (HUD 2021). Despite ongoing concern from policymakers and the public, we know relatively little about this highly vulnerable population. Answers to fundamental questions such as how many people experience homelessness on a given night, the level of deprivation homeless people face, how frequently they move, and their mortality patterns are generally based on inaccurate and incomplete data. For example, the most recent nationwide survey of the homeless population was conducted 25 years ago and relied on self-reported information (Burt et al. 1999). And while communities now conduct annual counts of their homeless populations, estimates are deemed unreliable due to reliance on volunteers with little or no training (O’Flaherty 2019, US Government Accountability Office 2020). Some recent studies use administrative data in specific cities or contexts to examine the effects of policies on homelessness, but they are unable to answer questions about the overall US homeless population (e.g. Evans et al. 2016, Fetzer et al. 2020).