Using recent advances in the classification of exchange rate regimes, this paper finds no support for the popular bipolar view that countries will tend over time to move to the polar extremes of free float or rigid peg. Rather, intermediate regimes have shown remarkable durability. The analysis suggests that as economies mature, the value of exchange rate flexibility rises. For countries at a relatively early stage of financial development and integration, fixed or relatively rigid regimes appear to offer some anti-inflation credibility gain without compromising growth objectives. As countries develop economically and institutionally, there appear to be considerable benefits to more flexible regimes. For developed countries that are not in a currency union, relatively flexible exchange rate regimes appear to offer higher growth without any cost in credibility.

We develop a novel system of re-classifying historical exchange rate regimes. One difference between our study and previous classification efforts is that we employ an extensive data base on market-determined parallel exchange rates. Our 'natural' classification algorithm leads to a stark reassessment of the post-war history of exchange rate arrangements. When the official categorization is a form of peg, roughly half the time our classification reveals the true underlying monetary regime to be something radically different, often a variant of a float. Conversely, when official classification is floating, our scheme routinely suggests that the reality was a form of de facto peg. Our new classification scheme points to a complete rethinking of economic performance under alternative exchange rate regimes. Indeed, the breakup of Bretton Woods had a far less dramatic impact on most exchange rate regimes than is popularly believed. Also, contrary to an influential empirical literature, our evidence suggests that exchange rate arraignments may be quite important for growth, trade and inflation. Our newly compiled monthly data set on market-determined exchange rates goes back to 1946 for 153 countries.

Drawing on new data and advances in exchange rate regimes' classification, we find that countries appear to benefit by having increasingly flexible exchange rate systems as they become richer and more financially developed. For developing countries with little exposure to international capital markets, pegs are notable for their durability and relatively low inflation. In contrast, for advanced economies, floats are distinctly more durable and also appear to be associated with higher growth. For emerging markets, our results parallel the Baxter and Stockman classic exchange regime neutrality result, though pegs are the least durable and expose countries to higher risk of crisis.

We show that "commodity currency" exchange rates have remarkably robust power in predicting global commodity prices, both in-sample and out-of-sample, and against a variety of alternative benchmarks. This result is of particular interest to policymakers, given the lack of deep forward markets in many individual commodities, and broad aggregate commodity indices in particular. We also explore the reverse relationship (commodity prices forecasting exchange rates) but find it to be notably less robust. We offer a theoretical resolution, based on the fact that exchange rates are strongly forward looking, whereas commodity price fluctuations are typically more sensitive to short-term demand imbalances.