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Numbers for Letters: the Zip Code Story

Ron Reiring on Flickr

As publisher of this magazine, one of the fun parts of my job is working with subscriber postal codes and addresses.

In Texas, for example, there are roads that include the letters FM, which means Farm to Market, because they are country roads that connect (or did at one time) the farms to the markets.

But, I can’t figure out Wisconsin addresses that begin with numbers like W273S3845: what do all the numbers after the W and the S mean?

On July 1, 1963, in the US, the ZIP code system was launched to replace what had been a more informal way to send letters and mail. ZIP means Zone Improvement Plan. It divided the United States into 10 zones and used four additional digits to identify the state and post office information. Another Four digits were added in 1983 to identify the side of a street address or location in a large building. These new digits also sped up mail sorting.

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To encourage people to use the newly installed zip code system, the post office did a lot of advertising. Santa was given the 99701 zip code, for example. Small towns realized that the new codes could improve mail delivery so they started adding numbers to houses, which helped even more.Of course, what interests me most is whether or not there is a 00000 zip code. Or a 99999 zip code. Or who lives in the 33333 zip code?

Sadly, zip codes only range from 00001 to 99950. But both are used in Alaska! 00001 is for the North Dillingham area while 99950 is Ketchikan. And when I looked up the 33333 zip code in a search engine, it appeared to be in Miami, Florida. But it is also used in South Korea and Mexico. This suggests the problem of how to send and deliver mail isn’t limited to the US.

These days, most people don’t send letters and have less contact with postal codes. But they remain an interesting technology that was created to solve the problem of sorting and delivering all the mail that goes through our national post offices.

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