Zone Improvement Plan codes, or what we commonly refer to as
ZIP codes, turned 50 recently! Yes, that’s right, they have only been in place
for 50 years – since the year 1963! The ZIP code is the system of postal codes
used by the United States Postal Service (USPS). The word “ZIP” is written
properly in capital letters and was chosen to suggest that the mail travels
more efficiently, and therefore more quickly, when senders use it. The basic
format consists of five numerical digits. An extended ZIP + 4 code (which was
introduced in 1983) includes the five digits of the ZIP code, a hyphen and then
four more digits, which allow a piece of mail to be directed to a more precise
location than by the ZIP code alone.
ZIP codes are numbered with the first digit representing a
certain group of U.S.
states, the second and third digits together representing a region in that
group (or perhaps a large city) and the fourth and fifth digits representing
more specific areas, such as small towns or regions of that city. The main town
in a region (if applicable) often gets the first ZIP codes for that region;
afterward, the numerical order often follows the alphabetical order .Generally,
the first three digits designate a sectional center facility, the mail-sorting
and distribution center for an area.
This piece by NPR highlights nine of the most noteworthy US ZIP codes. While census data is not technically available by ZIP code, it is available by something called ZCTAs. This stands for ZIP Code Tabulation Areas. These approximate ZIP codes based on their relationship to available census geography. To learn more about ZCTAs, visit
this Census Bureau webpage.
