NEW YORK (TheStreet) -- The longer Europe puts up with the fantasy that a single currency is essential to its prosperity, the longer Italy, Spain, Greece and others will flirt with financial ruin and self-destruction. No bailout can save the Mediterranean economies from recurrent crises as long as they use the same currency as Germany and other northern states.

When the

euro was established

in 1999, prices, debts and bank accounts were converted according to market-determined exchange rates. For Italy, prices and obligations were converted according to the average value of the lire against other currencies in the eurozone and those adequately reflected the competitiveness of Italian workers and its exports.

Over the next decade, productivity grew faster in the north than among Mediterranean states owing to differences in culture, geography and economic policy -- importantly, not all of those are within the control of national governments.

If Mediterranean economies had their own currencies, their exchange rates against northern currencies would fall in value to maintain price and wage competitiveness and employment.

Locked into

a single currency,

prices in the Mediterranean region became too high across an increasing range of products. The north enjoyed trade surpluses with the south, and governments in Italy, Spain and Portugal increasingly borrowed to hold down unemployment. In Spain, a rush of real estate investment -- government policies encouraging home ownership, and northern Europeans seeking second homes and vacations in its sunny clime -- permitted its banks to do the borrowing instead of Madrid.

The U.S. economy has similar problems -- worker productivity is higher in New York than in Maine and much of the rural south. However, Washington contributes substantially to government programs that shore up employment and incomes in lagging areas -- Brussels lacks such fiscal authority. Workers migrate to jobs in more productive and prosperous locations more easily in the U.S. than the European Union, because they share a common language and culture, and similar educational systems.

States get into chronic fiscal difficulties -- for years it was New York, and now it is California -- but not the kind of trouble Italy and Greece have fashioned.

When banks fail, the U.S. Treasury, Federal Deposit Insurance Corporation and

Federal Reserve

do the cleaning up. During the global financial crises, state governments, even if they had Washington's taxing capacity, could have never cleaned up Manhattan's financial institutions or shored up banks in places like Nevada and Florida whose problems mirrored those now arising in Spain.

In Europe, bank regulation, deposit insurance and responsibility for guaranteeing the solvency of banks are in the hands of national central banks and agencies. Without the capacity to print currency, the Spanish banking crisis demonstrates those national institutions lacking the resources and clout necessary to get the job done. In contrast, Iceland, facing similar challenges but having its own currency, is working its way out.

To have a common currency, Brussels must have the taxing authority to finance the social safety net throughout Europe, and the European Banking Authority and European Central Bank must have the power, resources and responsibilities enjoyed by the Comptroller of the Currency, FDIC and Federal Reserve.

To have political legitimacy, that requires a European federal government, and for Germany and other prosperous states to cede national sovereignty to it. That simply is not going to happen.

Sadly, Europe did quite well with national currencies and free trade within the European Economic Community. This is one of those rare occasions that bringing back the old -- national currencies -- simply recognizes reality and common sense.

This article is commentary by an independent contributor, separate from TheStreet's regular news coverage.

Professor Peter Morici, of the Robert H. Smith School of Business at the University of Maryland, is a recognized expert on economic policy and international economics. Prior to joining the university, he served as director of the Office of Economics at the U.S. International Trade Commission. He is the author of 18 books and monographs and has published widely in leading public policy and business journals, including the Harvard Business Review and Foreign Policy. Morici has lectured and offered executive programs at more than 100 institutions, including Columbia University, the Harvard Business School and Oxford University. His views are frequently featured on CNN, CBS, BBC, FOX, ABC, CNBC, NPR, NPB and national broadcast networks around the world.