Don’t Use Zip Codes in Geospatial Analysis

Matt Forrest of Carto says we should stop using Zip codes in geospatial analysis.

Even though there are different place associations that probably mean more to you as an individual, such as a neighborhood, street, or the block you live on, the zip code is, in many organizations, the geographic unit of choice. It is used to make major decisions for marketing, opening or closing stores, providing services, and making decisions that can have a massive financial impact.

The problem is that zip codes are not a good representation of real human behavior, and when used in data analysis, often mask real, underlying insights, and may ultimately lead to bad outcomes.

Zip codes, Matt says, are arbitrary: too many things going on at a local level can be missed if they don’t line up with zip code boundaries (such as the Flint water crisis). He does offer some alternatives: census tracts, spatial indices and good old fashioned addresses.

Meanwhile, on Twitter, Bill Morris defends the use of Zip codes: yes, they’re overused; yes, they should only be used in the worst case; but they may be the only local unit a client or user will find easy to understand.

Author: Jonathan Crowe

Jonathan Crowe blogs about maps at The Map Room. His nonfiction has been published by AE, The New York Review of Science Fiction, the Ottawa Citizen and Tor.com. His sf fanzine, Ecdysis, was a two-time Aurora Award finalist.