New area- and population-based geographic crosswalks for U.S. counties and congressional districts, 1790-2020
588/2021 Andreas Ferrara, Patrick A. Testa and Liyang Zhou
A common problem in applied research involves harmonising geographic units across time or different levels of aggregation. One approach is to use “crosswalks” that associate factors located within some “origin” unit to different “reference” units based on relative areas. We develop an alternative approach based on relative population, accounting for heterogeneities in urbanization within counties. We construct population-based crosswalks for 1790 through 2020, mapping county-level data across U.S. Censuses as well as from counties to congressional districts. Using official Census data for congressional districts, we show that population-based weights outperform area-based ones in terms of similarity to official data.