I often wondered if 42 could have actually been a card game some nine years before the domino game 42 was reportedly "invented" in Garner, Texas. I tried to find more information online but found none.
Recently, Jonathan Hatfield, a collector of vintage games, sent me some scanned images of the rules for Domino 42 (below), played with domino cards (above image). Thank you, Jon, for contributing the images for sharing with the 42 community.
Note: You can magnify text in the images below by mousing over the areas of interest. Adjust the zoom and size via the arrow keys on your keyboard: up/down (zoom factor) and left/right (magnifier size).
Research of copyright laws indicates the 105+ year old rules shown below are now in the public domain. (The U.S. Playing Card Company no longer has a curator.)Page 1
Page 2 (non-42 rules crossed out, other game rules omitted)