In a discussion following an article about Cold War fallout shelter crackers, the subject of blood type tattoos came up. This was a real thing in the early 1950s, that people, including children, would get their blood types tattooed on their torsos to streamline medical procedures during nuclear war. It was less for identifying the blood type of patients than for potential donors, but the area under the left arm was used because that would still be there if one's arms were blown away. We have literature about the tattoo programs in Indiana and Utah, although there were others. The Mormon Church even gave a dispensation on their rule against tattooing, calling it a "permanent imprint" instead of a tattoo. One woman shared her memories of getting a tattoo in Indiana when she was in first grade.
"The kid closest to the curtain was told to go inside the curtained area, and the rest of us moved up one chair closer. We then heard a buzzing sound similar to a dentist's drill, and a lot of screaming and, a few minutes later, the kid emerged from behind the curtain, crying, and then next kid took his place. The wait probably took about an hour, and during that time, as we inched closer and closer to the curtain, we had to witness each of our classmate's enter the curtained area and come out crying, so you can imagine how frightening it was."
"Once behind the curtain I had to take off my clothes above the waist and show my card and dog tag to the two people in there. Once held me still and the other stuck what looked like a power drill into my left side, turned it on and held it there for a minute or two. Naturally I was screaming and struggling just like the other kids before me."
"I still have my atomic tattoo (O-), but, as I grew it got distorted, so it's pretty illegible today. The tattoo caused a lot of comments during bikini season after I went to college and later moved to Ohio, where no one had seen anything like it. After I moved back to northwest Indiana I tried to search some public records but was never able to find any evidence of the program."