For decades the dollar has been the undisputed champ. It's not only the currency of America but much of the world as well, the fuel of global prosperity. As the superengine of the world's only superpower, it's accepted everywhere. When an Asian company trades with South America, those transactions are done in dollars, the currency of international business. But for how much longer? Economists fear America is digging a hole with an economy based on massive borrowing and huge deficits that cloud the dollar's future. Will the buck be eclipsed by the euro or even China's renminbi? Should Americans worry when the value of the mighty U.S. dollar sinks to par with the Canadian "loonie"? Craig Karmin's in-depth "biography" of the dollar explores these issues. It also examines the greenback's history, allure, and unique role as a catalyst for globalization, and how the American buck became so almighty that $ became perhaps the most powerful symbol on earth.