Edmund William Gilbert (1900–73) was a renowned British social and historical geographer. In this book, which was first published in 1933, Gilbert discusses the exploration of the western area of what became the United States during the first half of the nineteenth century. As part of this process, the text makes 'an attempt to reconstruct the geographical setting in which the explorers accomplished their work, and thus to estimate the influence of geographical factors on the history of the exploration of the region.' Numerous illustrative figures and a detailed bibliography section are also included. This book will be of value to anyone with an interest in historical geography and nineteenth-century American history.