It is a given that the United States has been an important global power, yet it may be of at least equal significance that the nation has been an only faltering planetary power. Global is social – it implies the social relations that extend over the globe. In contrast, planetary is physical, indicating the physical planet itself. Far more historical studies have focussed on the former than on the latter; examining the history of the United States within planetary terms is only beginning to be done. One long tradition of human engagement with the whole Earth is the practice of circumnavigation, going around the world. This essay examines American circumnavigators’ accounts ecocritically, in terms of their consciousness of the natural world, in order to explain that the United States came to the tradition of going around the world belatedly and not always beneficially.