I live out in the sticks, and there was a time not that long ago when many rural roads in Louisiana were unmarked. Someone decided to fix this in the 1980s, and we got "Parish Roads." However, no one seemed to do anything with these designations and eventually they just faded away. It wasn't until the advent of 911 in this area that there was a concerted effort to name roads and assign addresses.
Anyway, the Parish Road signs were removed at some point, but this one got missed somehow. It may be the only Parish Road sign left in the state, though I doubt that. It sits alone and forgotten along the road, its purpose lost in the mists of the past. Well, I remember you, "Allen Parish 134."
If you'd like to see more photos, you can find them in this Facebook album.