I was contacted by Lester S. who said the following:
We have a concrete base with number “191” marked into the concrete behind the rectangular seat base. It’s not set at an angle. Located in Washington County southern IL. I don’t think it’s a WPA unit but I’m guessing.
It sure looks to me like it could be another form for an WPA Outhouse platform. He sent me the above picture along with several others that are below. Does anyone out there have any idea if this was something else?
When you take a look at the concrete rectangle, it has a hole all the way down and the top could hold a wooden platform the could include the Outhouse hole along with a seat of some type.
Here are the other pictures.