This paper provides evidence that transatlantic commodity market integration began prior to the "first era of globalization" at the end of the nineteenth century. It does so by giving a long term perspective to the story of the development of an Atlantic Economy in wheat between the United States and Britain. Both trade statistics and contemporary comment reveal the importance of this trade from the middle to late eighteenth century, long before the so-called grain invasion of the late nineteenth century. Using data on imports from America and a large volume of substantiating primary evidence, specific periods are identified when market integration might have been possible. Using price data for wheat in America and Britain, some evidence is found that markets were integrated, but this process was continuously being interrupted by "exogenous" events, such as trade policy, war and politics. Transportation costs cannot be seen to be the driving force behind periods of increased trade, which are more attributable to the absence of these exogenous events.