@emilyjmacaulay It depends how much time you're willing to invest. One choice would be to find a genealogical society or club near where they lived, often these may maintain a library or files that you could donate to. Another would be to do some research to see if you could find and connect with current descendants and pass them along. Or locate/create them on FamilySearch's tree or #WikiTree and upload high-res scans of the materials to their entry. It might be nice to do that even if you can eventually donate them to someone else.