I found two post cards of the Reader Railroad recently. Here’s a link: Reader Railroad
It’s really annoying. I thought I had a handle on the dating of these cards, but, when I told a colleague about it, I realized that I had been totally wrong. The cards were printed by Koppel Kolor (or Color) Cards in Hawthorne, New Jersey. The company’s main building appears to have burned down in the mid 80s.
Update on the dating for these cards: mid-1960s. See comment below courtesy of thedigitalphilatelist
Blogging the Railroad Tunnels 
Hey – came across your site while researching Koppel. Based on the cat number on your cards, these were produced in the mid-60s. I work on Bahamas cards from Koppel and the series 74000 was produced in 1965 and the 89000 in 1969. So I assume your cards are probably within this period (79000).
Very much appreciated! This really helps out. Thank you!
The Koppel Kolor building is still standing and has been Lakeview Farms for many years. I have lived within a short distance of the building my entire life and even had a class trip to visit Koppel Kolor back in the early 80’s. I still have a few samples that they gave the class, including a little Kennedy Space Center booklet with pictures of many space rockets and early space shuttles that I cherish.
Thank you very much for the information!