First edition of this highly influential map depicting Baron de Lahontan's imaginary west-east Long River (Riviere Longue), rising in distant western mountains and emptying into the upper Mississippi.
The present example was almost certainly separately issued and bound into a composite atlas (with the #41 at the bottom right), with unusually wide margins.
The map extends east to the Great Lakes to show Lac Superieur, and Lac de Illinois (Michigan), along with a number of the early French forts and fur trading outposts. The detail in this larger format edition is noteworthy, showing the Pais de Mozeemlek, Pais de Gnacsitares, the boats used by various tribes, a typical community house of the Tahuglauk and other notes on Indian life. French and Indian settlements are shown on all the major rivers.
Lahontan's map was one of the most influential of all mythical cartographic works, effecting the cartographic landscape of the upper Mississippi, Plains and Rocky Mountain Region=s for nearly 50 years. Issued in N oueaux Voyages de M. le Baron de Lahontan dans l'Amerique Septentrionale, 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, quite possibly an anectdotal reference to the Columbia River, which Lahontan may have learned about from the Indians.
Lahontan's concept was copied by virtually all 18th-century cartographers, including Moll, Senex, Popple, and De L'Isle, thus perpetuating the myth.