One of the most important maps of the Northwest after the Lewis & Clark expedition. Charles Wilkes was the commander of the Wilkes Expedition, from 1838 to 1842. Wilkes carried out a survey of the Columbia River aboard The Porpoise from July to November 1841. The inset of the Columbia River survey on this map was taken from that expedition. It represented a tremendous advance in the mapping of the region. Wheat refers to the map as in many respects the most detailed of this extensive area yet published, and for the main Oregion region and the Hudson's Bay Company territories in the north it was…a quite extraordinary map. Wilkes sent a party up the Columbia and another south to California. He drew upon the information provided in recent maps by Hood, Arrowsmith and Parker, as well as manuscript information from Jedidiah Smith and the Hudson Bay fur traders. The result is the most important and accurate map of the period and a map of tremedous importance in the history of the cartography of the region. While the smaller edition of the map appears on the market with some regularity, this large format edition has become somewhat of a rarity. Offered here in attractive wash coloring. The original folds are re-inforced archivally on the verso, with some minor conservation and extension of the left margin for framing. In all, an excellent and very attractive example. Wheat 457.