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Intro to IPUMS NHGIS: Geographic U.S. census data, time series & crosswalks

Jonathan Schroeder headshot

Jonathan Schroeder
Research Scientist, IPUMS Center for Data Integration
University of Minnesota

Originally presented November 10, 2020

2020 Census Data will be released early next year and GIS professionals across the state will be some of the first asked to delve into the new population statistics. But older statistics about our communities are needed to answer important questions about how communities change over time. Where have population shifts occurred and how has the demographic makeup of these areas changed?

Answering these questions requires the use of historical census information and understanding “crosswalk” techniques to compare areas with dissimilar boundaries. The National Historical Geographic Information System (NHGIS) provides data to help with both. In partnership with the Tennessee Geographic Information Council (TNGIC), the Tennessee State Data Center is excited to welcome Jonathan Schroeder from the IPUMS Center for Data Integration at the University of Minnesota for our third fall webinar event.

The IPUMS National Historical Geographic Information System (NHGIS – provides free online access to summary tables and GIS mapping files for U.S. censuses and surveys going back to 1790 and for all summary levels down to census tracts and blocks. This webinar will provide an overview of NHGIS resources and demonstrate how to create customized data extracts. We will then delve into two unique NHGIS resources that facilitate studying changes across time: time series tables, which link together comparable statistics for multiple years, and geographic crosswalks, which support the allocation of data from one census’s units to another’s, enabling high-quality measures of change in small areas.

Jonathan Schroeder is a geographer at the IPUMS Center for Data Integration at the University of Minnesota, where he serves as a project manager and senior researcher for IPUMS NHGIS, leading the development of crosswalks, time series, and other resources. He also contributes to the IPUMS USA project by leading the development of integrated geographic variables for U.S. census microdata.