DT reader Moni flagged this in the September 1951 issue of Popular Mechanics. It's a do-it-yourself "traveling playpen" made from a couple of pieces of hinged plywood, custom fitted to the dimensions of your car's rear seat.
The article says, "[T]here is less possibility that the child will be injured if a sudden stop of the car is necessary." I'm pretty sure they meant "less uncertainty."
Plywood Platform in Back Seat of Car Makes "Traveling Playpen" for Child,' Popular Mechanics, Sept. 1951 [google books]
Wow. When I was a kid, mom had a Buick Century Wagon. She put a carpet in the "way back" and it was my playzone for long (and sometimes short!) trips. I remember having a lot of fun back there. This is the 80's we're talking about here, and seatbelts were still just catching on for many Americans.
Perhaps in 1951 the plywood playpen actually _was_ safer, since they probably didn't have seatbelts.
As a student of history, I learned very quickly not to pass judgment on the actions and mores of other cultures and civilizations, and to relate what people are doing to the context of the time period. But I have a hard time trying to figure out in what context this could possibly have sounded like a good idea.
But then again, I was recently rewatching the original French version of the film "Three Men and a Baby" (That's "Trois hommes et un couffin" to you, mon vieux) from 1985, and in one of the final scenes they just plop the baby into the flimsy umbrella stroller and put that in the car, in lieu of a car seat! So I guess we were all a lot less paranoid and/or a lot more clueless just a few short years ago.
I used to love hanging out in the "way back" of my parents' '83 Jeep Wagoneer, although I also remember my parents begin very conflicted over allowing me to be back there.
They knew it wasn't very safe, but they also knew that a 3 hour road trip would be a lot more pleasant for everyone if I could be playing in the way back with a pile of Legos and HeMan toys rather than strapped into a seat.
Eventually they replaced the '83 Wagoneer with an '89 Suburban outfitted with TV and VCR.
I carpooled to school for years sitting on a beanbag in the way back of a Jeep Wagoneer. I also rode in the back of pickups pretty frequently. It is amazing how things change in a short time- now I find myself scowling when I see a little kid in the front seat of a car, or a dog in a pickup.
I remember riding on top of the engine in the way-back of our VW bus. I was the youngest of 6, and that was my spot. It was so cozy, and a great place for a nap...yikes.
(aka Moni--I was typing-impaired yesterday)
I remember many a cross county trips in the back of the 70's station wagon with the rear window down and watching the stars.
In the 70's we had one station wagon that had a weight sensor in the front passenger seat that would buzz if you sat on the sensor and did not have the seat belt buckeled. We would shift our weight off the sensor or buckle the seat belt behind us (with Mom and Dad's permission of course).
We had all manner of dangerous riding - in the back of pickups (I would beg to do it whenever I had a chance), in very short beach chairs in the back of grandmother's big old wagon with the back window open, & my favorite, when I was very little, in the way back of a VW bug. Yikes. Oh yeah, and riding in the back of a Jeep with the gate (Gate? What the hell do you call that again?) down, on said gate with our legs dangling over the street. Only on the short trip home from the laundromat, mind you.