Testing for the economic impact of the U.S. Constitution

"Exchange rates and price indices are constructed to test purchasing power parity between eight British North American colonial locations, five of whom issued their own fiat paper money. Purchasing power parity is then tested between these same locations after six became states politically and monetarily unified under the U.S. Constitution. Purchasing power parity cannot be rejected between all colonial locations or between the six U.S. states, if anything holding with more confidence prior to U.S. political and monetary unification. But it is rejected between U.S. states and nearby British colonies that stayed outside the U.S. union"--National Bureau of Economic Research web site.