1918, 3¢ violet Offset, type III, Earliest Known Usage. Large margin single in combination with 2¢ Engraved (#499) on corner card cover to Canton, China, tied by "New York, N.Y., Apr 6, 1918" machine postmark, "Shanghai, May 8, 18" transit and receiving backstamps, two green Officially Seal, Chinese Post Office labels tied by Canton postmarks; light cover wear and slight crease in 2¢, F.-V.F., with this being the Earliest Known Usage of any U.S. Offset Lithograph definitive, the printing method was introduced as an austerity measure following United States entry into the First World War, an important cover of the Washington-Franklin period. Scott No. 529  Estimate $1,000 - 1,500. $0 (Image)