The French and Dutch referendums have dashed hopes of political union in Europe.
As criticism of the euro grows louder, there are fears that monetary union, too, might be in peril
The Economist "Can this union be saved?" June 6th 2005

Even before the euro was adopted, in 1999, it was clear that neither the EU nor the 12-member subset that has joined the monetary union was an optimal currency area.

Ideally, currency zones should be compact and homogenous enough to show little regional variation in business cycles—otherwise a one-size-fits-all monetary policy will leave some regions lingering in recession, while others grow so fast they overheat.

Many argue that this is what is happening in Europe, where a few countries, like Ireland, are experiencing rapid growth while big economies, like Germany and Italy, stagnate.

There are ways to mitigate imbalances within big currency areas. Even America is not an optimal currency zone; its regions sometimes boom or shrink out of sync with the rest of the economy. But America has important features that temper the problems of unified monetary policy

But America has important features that temper the problems of unified monetary policy. Federal programmes act as automatic fiscal stabilisers, siphoning off tax revenues from booming areas and transferring them to ailing regions as unemployment insurance or health benefits for the poor. America’s labour market is also highly flexible. This allows wages and prices to adjust downward, giving depressed regions a competitive advantage that can attract new companies and thus smooth out regional disparities. And workers in declining industrial towns frequently pack up and move across the country to find work; capital flows freely as well. Without these mitigating factors, people in depressed areas could easily be trapped in a cycle of stagnation.

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