Is there a zip code that equals its population?

I noticed yesterday that the population in a zip code near me is roughly equal to the zip code itself.

So I wondered: Does any zip code equal its population? Yes, it’s a silly question.

A zip code isn’t a quantity.

Populations are always changing.

Zip code boundaries are always changing.


The answer, according to the data I had on hand, is almost.

Smallest absolute error: Zip code 00674 has population 672.

Smallest relative error: Zip code 42301 has population 42319.

I’ve had to learn some of the intricacies of zip codes in the course of my work on data privacy.

I found out that zip codes are more complicated than I ever would have thought.

For one thing, the US Census doesn’t exactly report data by zip code but by zip code tabulation area (ZCTA) for reasons that make sense but are too complicated to get into here.

This is another reason why the question posed here is fuzzy; we don’t know the populations of zip codes unless they coincide with ZCTAs.

More on zip codes Distribution of zip code population Bits of information in a zip code This post started out as a Twitter thread.

The image above is a US stamp from 1973 promoting the initial use of zip codes.


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