The euro’s origins lay in the decision of 12 member-states of the European Community (now European Union) to establish an economic and monetary union, one of the pillars of the Maastricht Treaty in 1992.
Thus in 1999, the euro was introduced as a non-cash monetary unit. On January 1st 2002, euro coins and banknotes appeared in the participating states, subsequently becoming the sole currency of the countries, as their national currencies could no longer be used.
Other states subsequently adopted the currency.
Other notable events on January 1st:
In 1995, the World Trade Organization was formally established to supervise and liberalize world trade.
In 1863, US President Abraham Lincoln issued the Emancipation Proclamation, which freed enslaved people in the Confederacy.
In 1804, Haiti declared its independence from France.