A relic of a mailbox found in Brooklyn reveals something about how New Yorkers mailed letters

The Montauk Club House is an astounding Venetian Gothic building completed in 1891—when Brooklyn was a separate city and glorious townhouses made Park Slope one of the most architectural rich neighborhoods in New York.

While taking in the beautiful interior of the building, my eyes landed on a very utilitarian old-school mailbox tucked away above a radiator near the entrance.

On it was a message, asking users to remember to use “zone numbers” before they drop their letters in the box.

Zone numbers? I was unfamiliar with the term. But a 1960 document from the Brooklyn Public Library shows a map of Brooklyn divided into neighborhoods (third image), each assigned a different zone number.

I get it now—these zone numbers are the last two digits of each neighborhood ZIP code. Yet the mailbox also carried a sticker advising users to add the ZIP code to mail addresses.

Are ZIP codes a later version of zone numbers? According to the Library of Congress (LOC), ZIP codes were introduced nationally in 1963 to make sorting mail less time consumer for postal workers and therefore speed delivery.

But the LOC also explains that assigning towns and cities a unique number wasn’t a new idea; in 1943 the United States Post Office introduced zones numbers to many cities, and as the number of zoned cities increased over the next two decades, a new system had to be established.

So it seems the mailbox is carrying two separate messages: one from the early 1960s reminding people to use ZIP codes, the other possibly from as early as the 1940s asking users to add the zone number to the address.

ZIP codes have been standard in my lifetime, but apparently the switch from no code at all or a two-digit code was a big deal to people at the time. The LOC stated that it took until the end of the 1960s for the five-digit code to become widely used.

Here’s an example of a Greenwich Village antiques shop that had store signage still noting their two-digit postal code. (Sadly, the store is gone, but I appreciated the fact that they kept the code in their address, a vestige of another era.)

[Third image: Brooklyn Public Library]