Several years ago, I stumbled on a map so shocking to my modern workaday sensibilities that I couldn’t quite believe my eyes. “Oh, zounds, look at this old thing,” I almost certainly thought.

Forgotten map type no. 27: ‘Overlapping pattern pie chart map.’

We live in a time when the data visualization establishment will have you know that pie charts are garbage graphics only to be employed by foolhardy amateurs. Similarly, your friendly neighborhood Carto-vigilante will put you on notice for allowing something as vile as overlapping symbols to appear on a map. Occlusion be gone! 🙅‍♀️️🗺🙅‍♂

But there was a time when people made and proudly shared maps of all kinds with relative impunity. And I believed I’d found one of them. After all, it had overlapping… pie charts! So, I took to Twitter, declared it a “forgotten map type,” and went to bed.

Years (and countless throwaway tweets) later, I stumbled on that map again (so much for being “forgotten,” eh?) and pointed out its goofy New York label. In response, Toph Tucker noted he’d searched my timeline for more “forgotten map types” and come up empty. His comment was, simply, “well this is disappointing….”

Fair.

So, I slowly amassed a more complete list. And here it is. Most of these map types are silly or unusual, not forgotten. Many of them are even deliberately taken out of context to highlight their wackiness and how easily maps can be misread (I sure misread them all the time!).

It’s fun poking around the Internet Archive and HathiTrust, blowing the digital dust off of a volume with 0 views and having a look. You never know what you’ll find. Maybe a forgotten map type?