I thought Londonbus had a thread under
"Stamp Exhibitions" I could not locate it.
A lovely gift amongst ephemera from Collin (Thank you

)
1930 APS label.
It's a bit of an enigma, I know there are four in the set,
but that's about all.
I could find no information, on the exhibition, or the engraver
McKenzie Engraving Co Boston.
I find it hard to understand how they produce such an expensive looking label, for such a thing as an exhibition, and to boot
right around the time of the US stock market crash.
I guess it must have been produced as part propaganda for
the engraving business.
A beautiful specimen, none the less.