From the Political Economy 101 blog at EUobserver.com – Ireland and the Euro:
…the problem is that Europeans don’t want to accept that currency union means genuine economic and political union. In the USA, the individual states may have considerable autonomy (just as Canadian provinces or German laender do), but their economic survival is ultimately the responsibility of the federal government which issues bonds and can borrow on international markets. Think of what would have happened to Louisiana after Katrina had it been dependent on selling its own dollar bonds to the international market to raise money!
Others will argue, not without reason, that Europe has no polis, no shared political identity and culture. They tend to forget that until the mid-19th century, Americans identified far more with their home state or region than with Washington—and some still do. A shared political identity needs to be forged; it is the product of a vision which transcends local boundaries. At the moment, economic crisis is eroding any sense of European community we might have. That’s what ultimately could kill the euro.