<a href="https://en.wikipedia.org/wiki/Postage_stamps_and_postal_history_of_the_Canal_Zone" class="extiw" title="w:Postage stamps and postal history of the Canal Zone"><b>Postage stamps and postal history of the Canal Zone :</b></a>  Canal Zone air mail stamp, 1929 issue
U.S. Government / Canal Zone Postal Authorities -- Bureau of Engraving and Printing
Images obtained from eBay