now why had I never heard of this?

The Glendale, CA central library houses in its Special Collections Room the Cat Collection. As the Library website says,

This outstanding collection has drawn visitors, telephone and mail inquiries from all over the United States and Europe, as well as been featured in the Glendale News Press in an article entitled, "Purr-ient Interest."
The beginnings of the collection were given to the Library by the Jewel City Cat Club. In addition to the large number of books, the collection consists of paintings of champion cats, over 400 photographs by Hans Bomskow, posters, cards, stamps and stud books back to the early 1900's.

The collection was largely amassed through legacies left by local cat enthusiasts, but gets a little bigger every year -- by contrast, Yale's Collection of American Literature put the kibosh on accepting anything new of that persuasion. Here's an article about the Glendale collection. I can't believe I didn't know about this!