The Almighty Dollar

  Most Americans don't have to worry about currency.  In the US, we have one form of money: Greenbacks.  No drama, no problems.  My Econ prof brought up some very interesting points today in class.  He was talking about the general mistrust of the peso here in Argentina.  In Argentina, it began in the late fifties when the devaluing of the peso became common and inflation was at %100 annually.  And today, even the people that recycle cardboard for a living know the exchange rate between the Argentine peso and the US dollar. 
  He made the point that Argentina has two currencies.  I was told once that any amount that was 4 digits or more in pesos would be listed in dollars. And it's really true, small purchases are the only things that are handled in pesos.  All properties, vacation packages, and luxury cars are sold in dollars.
 This same professor recently bought a house in a high-end neighborhood of Buenos Aires. He never mentioned the exact price, but in one example, he used the term $300,000 USD.  And judging by the area of town, a two-story house is worth at least that much.  It was a very interesting process: In a room in the back of the bank, a notary checked over the contract, all spelled out in pesos. Then, the seller said, "Well, get the dollars."  So, the buyer walked down the hall to the teller and bought the dollars.  (The notary had informed the bank that on that day they would need x amount of dollars, cause he wants to get paid too).  The buyer carries the armful of greenbacks back to the room where another man counts them, under the notary's supervision.  
  Once everything is settled, the seller begins to divide money up into stacks of about $60,000 and gives them to his family members who were with him, mostly women.  They began to hide their money in their garments.  Money secured, the merry little band headed out to the car, which was parked three blocks away.  The buyer (my prof) told us that he felt so bad that he walked with them to the car, just for safety's sake. 
  He used this story to illustrate the system of two currencies. Then, asked us (a class of mostly Americans) what was written on our money.  Of course, the Portuguese student answers, "In God We Trust." The other is "This note is legal tender for all debts public and private."  He told us that in the States, you can't refuse someone who wants to pay you in dollars.  U.S. greenbacks are good for any kind of payment.  In Argentina you have the phrase "Traeme verde" - "Bring me green."  Pesos are often rejected.  
  Dollars is the currency of savings in Argentina, and most developing countries.  For example China's federal reserve is all in dollars, (about 20% of our GNP).  Brazil and Russia save in dollars too.  The whole world is looking for green. This gives strength to the States because they can keep printing money.
   The interesting thing is that even though it would seem to make more sense to save in Brazilian Reals or Chinese Yen (currencies of fast growing nations), the world continues to, overall, trust the dollar.  They always have. 
  All of this makes me wonder: What happens if the US is brought to a point where the government feels the need to devalue the currency?  I kinda feel like the whole world would be in trouble.  
But, I don't really know anything.