We have all become so accustomed to assuming that national currencies are the norm and preferable. In her book, 'Cities and the Wealth of Nations' (Random House, 1984) Jane Jacobs illustrates 'how national currencies stifle the economies of regions.'
She views the economy of a region as a living entity in the process of expanding and contracting. She understands the role of a regional currency as the appropriate regulator of this ebbing, flowing life. If a region does not produce enough of its own goods, relying heavily on imports, its currency is devalued. As a result, import costs increase, discouraging trade. At the same time, because the currency is less in demand, interest rates will decrease, thereby encouraging local borrowing for the production of 'import replacing' goods. Conversely, if the region is adequately supplying its own needs, then its currency 'hardens', that is, holds its real value relative to other currencies. As a result, imports are cheaper, encouraging trade, and interest rates higher.
The dependency on national currencies actually deprives regions of a very useful self-regulating tool and results in the paradoxical creation of stagnant economic pockets in a seemingly properous nation.