UPU colors

In 1896, Universal Postal Union (UPU) members agreed to standard stamp colors for international mail. This would allow faster processing of incoming mail. The standards set were: 
 * green for international basic printed matter
 * red for international post cards
 * blue for international first class mail



The US juggled their definitive stamp colors and became compliant in 1898. Japan did change its definitive and commemorative colors to reflect the change, but came up with a series that probably were not as most people would expect.

The system worked well for many years. However, as time passed and bicolor and multicolor stamps became the norm, the use of UPU colors was ended, sometime circa 1950. 



[[Category:U]]