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!