New Area- and Population-based Geographic Crosswalks for U.S. Counties and Congressional Districts, 1790-2020

A common problem in applied research involves harmonizing geographic units across time or different levels of aggregation. We provide crosswalks that allow researchers i) to harmonize U.S. county boundaries over time across Census decades and ii) to generate congressional district level variables from county-level data. The crosswalks include an area-based approach as in Hornbeck (2010), as well as the new population-based methods from Ferrara, Testa, and Zhou (2021), which are based on granular sub-county population information. We also provide teaching material to demonstrate the utility of these new crosswalks.<br><br><b>Reference:</b><br>Ferrara, A., Testa, P.A., and Zhou, L. (2022) "New Area- and Population-based Geographic Crosswalks for U.S. Counties and Congressional Districts, 1790-2020", SSRN working paper: https://dx.doi.org/10.2139/ssrn.4019521