Many places have more than one official currency. Many more have more than one unofficial currency. The USD is unofficially used as a currency in many, many c

Many places have more than one official currency. Many more have more than one unofficial currency. The USD is unofficially used as a currency in many, many countries around the world, as an adjunct to the local currency. In the days before the Euro, it was quite common for places to accept multiple currencies in the one location, especially in border areas or smaller countries with lower floats. It's not such a big deal. Just about every international traveller works in two currencies by converting the 'away' currency into their 'home' currency in their head with each purchase. I have actually been offered the opportunity to pay with my home currency on visa POS machines while travelling. There are undoubtedly efficiencies to having a central currency, but when the central government is systematically destroying the unit of value, inefficiency of multiple currencies is a very small price to pay for being able to escape that. That's why Zimbabwe has the highest number of currencies on the list that was linked above [Edit: position is relative, the list that ianb linked]