Crosswalking ZIP Codes to Census Geographies: Geoprocessing the U.S. Department of Housing & Urban Development’s ZIP Code Crosswalk Files

Alexander Din
U.S. Department of Housing and Urban Development

Ron Wilson
U.S. Department of Housing and Urban Development

Disclaimer: The views expressed in this article are those of the author and do not represent the official positions or policies of the Office of Policy Development and Research, the U.S. Department of Housing and Urban Development, or the U.S. Government.

Although ZIP Codes are a commonly used geographic unit for mapping and spatial analysis, they frequently distort data (Beyer, Schultz, and Rushton, 2007; Cudnick et al., 2012; Dai, 2010; Grubesic and Matisziw, 2006; Hipp, 2007; Krieger et al., 2002; Montalvo and Reynal-Querol, 2017; Wilson, 2015). ZIP Codes are designed for efficient mail delivery, not for geographic analysis. The large area that ZIP Codes cover make them susceptible to data aggregation problems that corrupt local geographic patterns. Due to the irregular—and often contorted—shapes of ZIP Codes, smaller geographic boundaries are ignored when overlain with smaller geographies, to which population counts are disproportionally distributed between the multiple areas that are cross-cut. The U.S. Department of Housing and Urban Development (HUD) provides several crosswalk files to estimate incident counts at different geographic scales from data at the ZIP-Code level.