On this day in 1921, the Communist Party of China was founded.
On this day in 1963, ZIP codes were introduced for United States mail.
On this day in 1980, "O Canada" officially became the national anthem of Canada.
On this day in 1990, East Germany accepted the Deutsche Mark as its currency, thus uniting the economies of East and West Germany.
On this day in 1997, China resumed sovereignty over Hong Kong, ending 156 years of British colonial rule.
And on this day in 2007, smoking in England was banned in all public indoor spaces.