> In terms of the Euro, I find it more useful to view the Eurozone as somewhat similar to the US. There's one central monetary policy for really large economies that in a different environment, would have liked to do things independently. It's especially relevant now as US states have GDPs comparable to the Eurozone constituent nations.

There is an enormous difference, though: internal mobility/identity.

Germans tend to strongly prefer living in Germany. Greeks tend to strongly prefer living in Greece.

People in Oregon and New Hampshire tend not to have very strong affection for their state.

Which means that, if one area is economically depressed at the same time that another area is booming, the problem tends to sort itself out as people move from the struggling area and to the prosperous one.

In Europe, that just doesn't happen to nearly the same extent.