 Beforehand the domestic rates of postage in the United States were made applicable to all possessions of the United States on June 20, 1904, which henceforth included the Canal Zone.The first Panama stamps consisted of existing Colombian stamps, which were overprinted with "Panama".These in turn were used for Canal Zone postage and were again, overprinted with "CANAL ZONE" with a red bar at top blocking out the name "Colombia".