Vacant houses are often pointed to as a symptom (or cause) of the housing crisis, but what do we really know about them? Where are they located; who lives in them; how many are there? In this conversation we explore foundational, data-driven research on the nature of vacancies in cities and neighborhoods across the U.S. with Professor Jake Wegmann of the University of Texas at Austin. We focus on “ghost dwellings” — houses that are vacant most of the year and primarily seasonal or recreational in use — and discuss their surprising distribution around the country and within cities, what may be driving their proliferation, and how policymakers and advocates should respond to them.