In 1801, Zadok Cramer published the first edition of his Navigator river guide. Charles Dahlinger explains that Cramer “had been in Pittsburgh but a short time when he realized the necessity for a publication giving detailed information for navigating the Western rivers”. In 1803, the United States acquired the Louisiana territory and doubled its size. The Mississippi river became the Frontier, the starting point of the West and of the Lewis and Clark expedition a year later. Then, there were eight more editions of Cramer’s Navigator, actualizing geographical, economic and demographic data. As a printer and editor, he was implicated in the economic and cultural development of the West. But beyond the conventional, scientific and coded form of the travel guide, the text invites the reader to imagine himself as the navigator but also as a future citizen of the Mississippi Valley. This communication aims at showing how Cramer, in shaping the geographical features of the Mississippi Valley by the means of his narrative, led the reader to include it in the geographical and cultural boundaries of the United States. Through the use of many rhetorical devices, Cramer attenuates the borders between non-fictional and fictional travel writings to shape the new face and identity of the American territory. John Rennie Short assumes that “[t]he construction of a national identity involved the creation of a national geography”6. The main textual characteristics that this study wants to outline are of a narratological nature. The way the Mississippi river is described in the text reveals the presence of a narrator hose intentions clearly are to project the reader on the Father of Waters and its surroundings to inscribe this new territory in the national geography. Thus, added to narratology, this analysis requires reader response theories to understand how the readership is included both in the text and in the space described.