stamps honoring the various members of the Commission, were: 1¢, Gorgas, 2¢ Goethals, 10¢ Hodges, 12¢ Gaillard, 14¢ Sibert, 15¢ Smith, 20¢ Rousseau, 30¢ Williamson, and 50¢ Blackburn. Canal Zone permanent and provisional issues have since replaced all overprinted United States stamps and stamped paper. 1939 25th anniversary issues On August 15, 1939 the Canal Zone Post Office issued a series of 16 stamps commemorating the 25th anniversary of the canal's completion, depicting "before" and "after" views of various points along the canal. Thereafter stamps appeared at an average rate of about two per year, with a commemorative set in some years and no stamps in others. The inscriptions were changed to just "CANAL ZONE" in the 1960s. This paralleled the abandonment of the word "POSTAGE" on many United States stamps, as the United States ceased to issue revenue stamps. The last such item replaced was the 2 cent postal card on November 1, 1958. In 1928, the Zone issued a definitive series inscribed "CANAL ZONE POSTAGE" depicting various persons involved in the construction of the canal, as well as a 5 cent value showing the Gaillard Cut. 1946–1949 issues Between 1946 and 1949 five notable figures connected with the promotion and construction of the Canal Zone were commemorated on its postage. Gold rush issues On June 1, 1949, the Canal Zone issued four stamps commemorating the 100th anniversary of the California gold rush. Printed by the Bureau of Engraving and Printing, the stamps underscored the Isthmus of Panama's significant role as a major crossing point for gold seekers en route to California. They remained on sale until August 11, 1952, after which remaining stocks were destroyed. 1951–1960 issues Air mail issues The first Canal Zone air mail stamps were issued in 1928—1929, with rates of postage over-printed on existing Canal Zone permanent issue stamps, issued in 1929. 25th anniversary air mail issues In 1938 the Canal Zone Postal Authorities issued a series of stamps commemorating the 25th Silver Jubilee anniversary of the opening of the Panama Canal, and the 10th anniversary of airmail service there. This series was printed on the flat plate printing press. Winged globe issues The Globe and Wing airmail stamps were issued 1951—1958 a six-stamp series replacing the Gaillard Cut permanent series with a more modern depiction of a winged airmail allegorical image. The image is superimposed on a depiction of a map of the