In a process that began with the Maastricht Treaty of 1991 and concluded on January 1, 1999, 11 Western European countries made the euro the European Union's single currency. Bringing together Germany, France, Italy, and other European countries into a monetary union with a single currency and a single monetary policy could only ever result in major imbalances between the member countries, thus threatening the EU itself. This was recognized from the start by many economists and other observers. No one really followed up on these risks in terms of actions and reforms, until things changed dramatically with the financial crisis of 2007-2008.
