Does leaving a currency union reduce international trade? This paper uses a historical approach to re‐examine the puzzling large apparent impact of currency unions on trade. I find that the early time series estimates were driven by the gradual decaying of colonial trade ties and other major geopolitical factors, including warfare, communist takeovers and ethnic cleansing episodes. My methodology, which carries lessons for other uses of gravity equations in policy analysis, yields point estimates of currency unions on trade that are not statistically distinct from zero.