Euro in Madrid. The euro was introduced to world financial markets as an accounting currency on 1 January 1999, replacing the former European Currency Unit (ECU) at a ratio of 1:1 (US$1.1743). Physical euro coins and banknotes entered into circulation on 1 January 2002, making it the day-to-day operating currency of its original members, and by March 2002 it had completely replaced the former currencies. While the euro dropped subsequently to US$0.83 within two years (26 October 2000), it has traded above the U.S. dollar since the end of 2002, peaking at US$1.60 on 18 July 2008. In late 2009, the
De facto currency De facto currency A de facto currency is a unit of money that is not legal tender in a country but is treated as such by most of the populace. The United States dollar and the European Union euro are the most common de facto currencies. Andorra used the euro unofficially prior to June 2013, at which point the euro became its official currency. The euro remains the de facto currency in Kosovo and Montenegro. Countries using the United States dollar as their de facto currency include Aruba and Cambodia, where most hotels, restaurants, and transportation are priced in dollars;