https://www.thepacker.com/opinion/great-green-pepper-mango-mystery
I’d heard of it before here and there, and a close friend from IN was familiar with it - as a German i just found it puzzling to the max. I recalled there being a pickled component to it, and there is.
Here’s a (more) comprehensive explanation (than I could ever remember).
Some years ago I had looked into this mango-pepper confusion. Don’t have time to hunt for my notes from then, but the following may be of interest:
Here’s more:
Wow, thx for sharing. Really appreciate it 
I’ve glanced through my notes and it appears my interest in this mango-pepper confusion arose at a workshop I attended at the Schlesinger Library in 2009 on historic cookbooks. A few of us noticed in the books that we were reading that the word “mango” was used in English and American food books from the 1700s on to mean a pickled something: “mango of cucumbers” and so forth. The earliest reference we could find was the one the OED quotes from John Evelyn’s 1699 “Acetaria: A Discourse of Sallets”. Yet, the use of the word in this way is so matter-of-fact that I, at least, was convinced there had to be earlier usage. But I failed to find one.
I mentioned this in an unrelated thread where @HappyOnion and I were going off the rails.
As a kid and even into my young adulthood, my maternal grandparents always called them mangoes. People who shopped their small grocery did too. Even stuffed baked bell peppers were called “stuffed mangoes”. When we visited my mother (who called them bell peppers at home in our state) called them mangoes there.
I tracked it down some years ago when it came up on CH. Going from memory, it seemed to exist in a fairly narrow horizontal band running at least from Ohio, through Indiana, Illinois, and Southern Iowa/Northern Missouri. Some references also claimed small parts of PA, KS, KY had the usage, but that it didn’t persist as long as in the other states. I heard it from old folks at least into the mid-1980s, but certainly no one in my generation around my parts (IL, IN) clung to it.
I’m pretty sure I did not have real mango until I was in my 20s, in the Army.
