Zillow Transaction and Assessment Database (ZTRAX) Finds New Home at ICPSR
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ANN ARBOR — The nation’s largest housing and real estate dataset, the Zillow Transaction and Assessment Database (ZTRAX), is now available to researchers via ICPSR at the University of Michigan Institute for Social Research.
Zillow discontinued distribution of ZTRAX in October 2023. This transition restores access to a high-value resource, unlocking a wealth of public records spanning more than 20 years and over 2,750 US counties. The renewed availability of ZTRAX at ICPSR opens new possibilities for social science, housing, and real estate research, enabling scholars to gain insights into market trends, segregation patterns, land use and environmental impact, and much more.
The data collection includes over 20 years of deed transfers, mortgages, foreclosures, auctions, property tax delinquencies, and more, covering both commercial and residential properties. Property characteristics, geographic information, and prior valuations are available for about 150 million parcels nationwide. ZTRAX does not contain Zestimates, rental or listing data, or user search data. The dataset will be updated regularly, and researchers are encouraged to download only the geographical subsets relevant to their work to manage its large size.
ICPSR’s Amy Pienta, Director of Data Acquisitions, said ZTRAX is an essential tool in studies of residential segregation and other social science questions. “It is structured to be merged with other datasets for multi-faceted research, and ICPSR’s dissemination fills an important gap left when Zillow’s original program ended,” Pienta said. “Researchers will find ICPSR’s resources and code repositories helpful for working with these rich data and pursuing innovative analyses.”
Researchers interested in using ZTRAX can visit ICPSR’s ZTRAX study homepage to apply for data access. Additional support—including documentation, code repositories, and community best practices—are also linked from the study homepage, such as GitHub repositories for dataset creation and importing ZTRAX files into R or SQL databases. These data are restricted access, but documentation can be downloaded. They are distributed exclusively through ICPSR and are freely available to users at ICPSR member institutions. If you are not affiliated with an ICPSR member institution, you can still apply for access—details can be found on the ZTRAX study homepage.
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