This problem of material preservation is like internet security: it is a goal, but never a certainty. 

Data on steam era freight cars is preserved better than you might have expected from reading the few hobby and historical magazines of the 80s, but then came the ability to replicate and share through electronic media and boom, we find all kinds of info was out there.  Still, we will only lose information over time (media in any format--magnetic, film, paper, stone--degrades).

I had an interesting event--a house fire in 2015.  I possessed the correspondence files and as many extant photos of a small shortline in North Carolina that I could manage to obtain.  I had begun a process of scanning all the correspondence and photos to electronic formats to have something to analyze after I donated the material to a more permanent organization.  While the edges of the paper and photos (in archival sleeves) were singed and the paper smoky, they managed to survive a fire that put us out of the home for 8 months while it was being repaired. In contrast, the electronic scans were all irretrievably lost even after the insurance company paid to have a specialist company try and retrieve them from my hard drives (I had copied the data to multiple drives, including a portable one that I used as external backup, but brought home every weekend from my brother's house to update. The fire happened on Friday night while the backup was with me to update.   Interestingly, some CD read write discs did survive and were retrievable, though most were damaged and only partially readable if at all.   So hard copy survived better than electronic data that time .

Why am I scanning the material again?  This time, I'm sharing the electronic info in an effort to disperse it widely.  Maybe only one copy of Aristotle survived until the printing press was invented, but now there are thousands, even millions of copies and we're a lot less likely to lose them all over time.  I'm sure there will be fidelity loss, but that is nothing compared to the complete loss.   So as I scan the correspondence, the conductor's logs, the photos, and even the ICC valuation reports, I put them on 16GB hard drives and share them with those who are interested and willing to store it, and even share it more widely.  

While many of the photography collections may be lost or "buried" in organizations without funds to catalog or share them, some of those photos are found because they are published--that is multiple copies were made and distributed.  If you have a favorite photo, drawing or other documentation of a steam era freight car that you hope to see preserved, I suggest you try and write an article for an historical society journal or magazine, even for a modeling magazine, or share it with someone writing a book.  Either that, or copy and share it as widely as you can.

Take a strategy from nature: either put all your eggs in one basket and protect it as much as you can (e.g., redwoods, elephants, humans), or go crazy creating copies and hope at least a few survive (frogs/tadpoles, bacteria).  Nothing is guaranteed, but some strategies seem to work better or longer.

Best,

Dave

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David Bott, modeling the A&Y in '34