Postal Museum
The King of Chinese Stamp had dreamed of forming the first Chinese postal museum but was unable. Walking into the Postal Museum near the Union Station in DC, the first post I saw was Pacific Exchange China & US Mail 飞越太平洋 中美邮件交流
How mails were delivered in the past – mailman (no female?) made marks on the tree so he could get back.
Postmarks in space … and the 1918 Inverted Jenny
