But this Jan. 1 the euro became the mandatory circulating currency in the 12 countries forming the European Monetary Union.

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And just as you don't need more than one currency circulating in a domestic economy, so you don't need more than one global reserve currency.

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The Netherlands, along with 11 of its EU partners, began circulating the euro currency on 1 January 2002.

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This banknote liability arises largely because the bulk of the euro currency circulating outside the eurozone is sourced from, and paid for in, Germany, meaning that the Bundesbank holds a much greater share of refinancing loan assets backing the euro banknote circulation than its statutory allocation.

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Bay Bucks are a local currency--one of a handful circulating in the U.S., including Burlington Bread, Ithaca Hours and, soon, BerkShares in Massachusetts.

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