It’s hard to believe, but the zip code, that five-digit number that helps your mail get to the right place, has been around for just fifty years. The Zone Improvement Plan was, however, built on the foundation of earlier attempts to make our mail system more automatable.

In 1943, the amount of mail being sent was growing steadily and many of the experienced postal staff were going off to fight in WWII. To help make things easier on the new employees, the largest cities in the country were given one- or two-digit postal zone codes, to be included in the address after the city and state. These zone codes “faced little opposition and caught on quickly with businesses and the American public” (source). Two decades later, on July 1, 1963, the post office tacked that number onto the end of a three-digit sorting facility number to create the zip code we know today. This time the change didn’t exactly catch on like wildfire. Why?

According to the National Postal Museum website, “With fear of Communism still strong in Cold War America, some people feared that the creation of ZIP Code was a conspiracy to depersonalize or dehumanize them.” Others were simply annoyed that, on the heels of having to learn to use area codes with their telephones, they now had to know not just their own five-digit zip code, but also the code of anyone they had to send mail to! (source).

Today, we dip into the collections in Acumen to see how letters were addressed in the years before the advent of the zip code, and just how long it took for people to get the hang of it!

This post(al) card from 1882 doesn’t seem so strange:

Apparently, though, a street address or even a place of business wasn’t necessary:

And you could put the details of the address wherever you wanted:

You might include the county as well as the city and state. Notice that we’re still not big on street addresses yet — and why should we be, if there was no local mail delivery.

Sending local mail didn’t require much explanation…

…even as late as 1937!

This card in 1917 shows the postal address becoming more standardized:

Or was it?

We were moving toward familiarity in the 1920s-1950s:

Then came the zip code! In the decade of its introduction, its use was pretty sporadic, if the Pauline Jones Gandrud Papers are any indication.

Here is Mrs. Gandrud’s address, including zip code, in 1965:

Here is mail addressed to her from 1966-1968 with no zip code:

By the 1970s, though, more of Pauline’s letters were coming in with a zip code, including this one, with the zip code emphasized:

For a lot more history of the zip code, including a discussion of the zip code campaign’s mascot, Mr. Zip, see the Smithsonian National Postal Museum website.