Still going through my mom’s stash, and found a deck of World War II airplane spotter cards. Not only are they in spotless condition, but all fifty-two cards are in the deck! Heck, I can’t keep a new deck together for six months, let alone 70 years.
Radar was not as effective at that time as it is now, and a German U-boat was found
off the Atlantic Seacoast, so Americans were very much at risk from foreign invasion. These cards were used by mainly by civilians (a few military users) to familiarize themselves with the shapes of various aircraft.
thisendoftheswamp 
Once upon a time, wanting to be a pilot, and spending my days identifying the planes that flew over our house on their approach to Sea-Tac (yeah, they dropped their landing gear over our backyard) . . . those are WAYYY COOL!!