Great stuff this weekend. Very nice portraits Irv. Flippy, that old train photo is interesting. I wonder if they made negatives from the glass plate to distribute it. I have seen copies of negatives on sale that were press photos distributed to publications like newspapers.
Yes, it came from the estate of a man who worked for a trade paper back in the 40s and 50s, and most likely was printed in whatever periodical he was working for. It's a photo of a retouched photo, with some additional work done on the negative itself. The photo of the locomotive is well known, however most of the images floating around online are of a very poor quality (see below).
Interestingly, a railway historian I am in contact with owns a salt print of the same photo, likely made in the 1850s, very fragile but still in rather good shape for its age.
The car in your mother's photo BTW looks like a 1949 Plymouth, but it's hard to be sure (could be a Dodge of a similar year).