Creating the European monetary union between diverse and unequal nation states is arguably one of the biggest social experiments in history. This book offers an explanation of how the euro experiment came about and was sustained despite a severe crisis, and provides a comparison with the monetary-financial history of the US. The euro experiment can be understood as risk-sharing through a currency that is issued by a supranational central bank. A single currency shares liquidity risks by creating larger markets for all financial assets. A single monetary policy responds to business cycles in the currency area as a whole rather than managing the path of one dominant economy. Mechanisms of risk-sharing become institutions of monetary solidarit...