An Easy Communication Betwixt the River Meschacebe and the South Sea

The French followed the Portuguese, Spanish, and English to the New World. Contact with the Indians of the region led to a lucrative fur trade and a keener sense of American geography. By the early 1600s, the fur trade expanded westward, moving inland up the St. Lawrence River. Reports from western Indians of “Great Waters” even further to the west raised hopes of finding a water route to the Orient.

French coureurs de bois, or trappers, were undoubtedly the first Europeans to reach the northern Mississippi. In 1682, René Robert Cavelier, sieur de La Salle, descended the Mississippi River, proving the river emptied into the Gulf of Mexico. La Salle claimed the Mississippi and all lands drained by the river and its tributaries for France, naming the territory Louisiane in honor of Louis XIV.

Over the next eighty years, the French—adventurers, traders, miners, missionaries—explored most of the territory that lay between the Appalachian Mountains and the Rocky Mountains in present-day Canada and the United States. The era of French explorations in the New World came to a close with the fall of Quebec in 1763 and the cession of Louisiana to the Spanish in 1764.

In addition to their legacy of extensive explorations, the French developed two geographical theories that played an important role in cartographic representations of western North America. The pyramidal height-of-land theory postulated that America’s great rivers all originated from centralized mountain heights before they dispersed to outlets in the Mississippi River, Hudson Bay, or Pacific Ocean. The French believed the sources of the rivers to be so close together that a short portage between them might be possible.

The second geographical theory, known as symmetrical geography, held that the topography of the western half of the continent was a mirror image of the continent’s eastern landforms and waterways. Thus the drainage patterns of the rivers on the Pacific slopes of the western mountains would resemble those of the rivers on the eastern side of the Appalachian Mountains. Further, once the construction of an eastern canal from the Potomac River to a tributary of the Ohio River appeared feasible, proponents of symmetrical geography believed that a similar internal improvement linking the rivers on the Pacific side of the continent might also be possible. A half-century later, one of the principal objectives of the Lewis and Clark Expedition was to resolve these geographical conjectures.

Knowledge of the French explorations spread among those most interested in American geography. Cartographers produced maps based on information gleaned from the field journals and letters of adventurers and explorers. Immensely popular “pulp” journals rapidly disseminated information about the French discoveries. Sensationalized accounts by Hennepin, Baron de Lahontan, Daniel Coxe, Pierre de Charlevoix, and Jonathan Carver contained a mix of firsthand investigations, information borrowed from other legitimate sources, and outright fictions. These journals touted the ease of reaching the Pacific Ocean.

Thomas Jefferson was well aware of the French adventures in the West. Both the legitimate and the exaggerated accounts helped form Jefferson’s image of the West and spurred his romantic hope of finding a water route to the Pacific Ocean.