This 4 cent stamp was issued by the United States Postal Agency in Shanghai in 1922, created by overprinting a 2 cent carmine stamp from the Washington-Franklin series for use in the U.S. Offices in China. Printed using offset lithography with line perforation 11, this issue was part of a unique dual-currency postal system for American citizens and diplomats in treaty ports such as Shanghai. The overprint "SHANGHAI / CHINA" and surcharge "4¢" served to align with Chinese postal rates. It features a profile of George Washington, a recurring symbol of American governance and stability, overprinted in black ink. Catalogued as Michel US-CN 18, Scott US K18, Yvert et Tellier CN-US 18, Stanley Gibbons US-CN 18. Condition: Used with a well-centered violet-black Shanghai circular cancel, strong color and intact perfs. Estimate "$55 – 65".