China 1919 United States Postal Agency in Shanghai 1919 surcharges set of 16, SG1/18China United States Postal Agency in Shanghai 1919 surcharges set of 16 to $2 on $1 purple black. Also includes 1922 2c on 1c blue green and 4c on 2c carmine, SG1 18. These stamps represent all issues of the United States Postal Agency in Shanghai which was open from 1 July 1919 to 31 December 1922. They were valid for use on mail despatched from the US Postal Agency in Shanghai to addresses in the United States. A nice well centred mint and fresh