Center for Studies in Demography and Ecology

ZIP Code Crosswalk: Beta Testers Needed

Posted: 6/4/2019 (CSDE Research)

CSDE Visiting Affiliate Amy Bailey and her co-author, University of Illinois-Chicago doctoral candidate Allison Helmuth, invite beta testers for a new ZIP Code crosswalk they have developed. The crosswalk covers the entire US and spans years 1990-2010. The beta test crosswalk is available via a Stata .do file and an Excel spreadsheet. You can request access here. In exchange for accessing the Crosswalk, the authors ask that you provide feedback about your experience, which will help them finalize the data tool for public distribution. Please contact Amy Bailey with any questions.

Bailey and Helmuth used a biweekly administrative publication circulated by the US Postal Service to identify changes affecting the spatial boundaries of 5-digit ZIP Codes, such as anytime a ZIP Code boundary is created, broken up, or merged with another, including the date of implementation. They then created spatial cluster codes to reference the smallest indivisible geographic unit that remained constant over each decade (1990-2000 and 2000-2010), allowing researchers to minimize the potential for measurement error in their analyses of ZIP Code level data.

Roughly 1,000 ZIP Codes are affected by these boundary changes each decade, challenging researchers’ ability to correctly link ZIP Code-referenced data with the appropriate aggregated social, economic, and demographic characteristics. These boundary changes tend to occur in places where populations are rapidly expanding or contracting. Bailey and Helmuth also identified hundreds of ZIP Codes that refer exclusively to P.O. Boxes, rather than a geographic area.