This crisply engraved and significant map was issued just two years before the official report of the Lewis & Clark expedition. According to James Walker's thorough "Cartographic First Fruits of the Lewis and Clark Expedition" (see references), Poirson's map of North America is "the most advanced of the pre-1814 maps depicting the western interior." It is one of the early few to locate where Lewis & Clark wintered (Fort Mandan), the three forks of the Missouri (Galatin, Madison and Jefferson), and a more complex system of mountains. Also significant on the western side of the Rockies, the Clearwater River is shown connecting to the northern branch of the Snake River and on to the Columbia River. To the south, Poirson's depiction of the Southwest is taken directly from Humboldt. It is worth noting that Porison prepared Humboldt's map of Mexico in 1811, meaning he had complete access to his work.

Political delineations are also of interest on this map, as the United States' recently acquired Louisiane extends to the Rocky Mountains, with the Oregon region shown as a British possession. To the south of Oregon are Spanish possessions, including a named Texas. There is limited inland detail consisting mainly of rivers and Indian tribes, with a a large section marked Pays Inconnu. The map extends to include the Caribbean islands and northern South America. Decorated by a simple oval title cartouche and six distance scales. From the 1812 edition of Nouvel Atlas Portatif.

References: The Portolan #64 (Winter 2005-06) pp. 9-24.

Condition: B+

Issued folding on watermarked paper with light offsetting.