Nice example of Lahontan's map of Canada, from Acadia and he mouth of the St. Lawrence to the upper Mississippi River and the Grand Lac des Assinipoval, centered on the Great Lakes.
Lahontan's maps and most notably the map showing a western River extending to the Pacific, were among the most influential of all mythical cartographic works of North America, effecting the cartographic landscape of the upper Mississippi, Plains and Rocky Mountain Regions for nearly 50 years.
Issued in Memoires de l'Amerique Septentrionale ou la Suite des Voyages ...., one of the most influential and fanciful works of its time. The map depicts the Longue flowing from the mountains in the west (Rocky Mountains), home to the Gnacsitares Indians, and connecting to the Mississippi River. On the western side of the mountains is another river, presumably flowing into the Pacific.
Lahontan's concept was copied by virtually all 18th-century cartographers, including Moll, Senex, Popple, and Delisle, thus perpetuating the myth.