I am a fan of post office memorabilia and I purchased this set of signs from a friend who found them in the basement of the post office building in Rushland, PA.
They are 4 feet long and just under two feet wide. I am attaching a picture of another post office from the same time period in Penn's Park, and you can see a similar post office sign that must have been made by the same company or individual.
I know this was made in the late 1800's - and have been searching for any other signs like this, but haven't found any. Would love any context or additional information if anyone knows.