This map is one of the cornerstone maps of the American West. Carl Wheat noted “in the history of the American West, the year 1848 is signalised by three events above all others, the discovery of gold at Sutter’s Mill … the formal close of the Mexican War … which brought the cession of California and New Mexico … and the creation of the Territory of Oregon … All three events figure in the characteristic maps produced during the year, and particularly the cartographic monument of 1848, the magnificent ‘Map of Oregon and Upper California” (Wheat, 49).

Fremont had been court-marshalled and dismissed from the Army in 1847. He was not therefore asked to publish the results of the last expedition of the Corps of Topographical Engineers. It was due to his father-in-law, the powerful Senator Thomas Hart Benton that the report was published as ‘Geographical Memoir’, otherwise known as Misc. Doc. No. 148, 30th Congress, 1st Session. To accompany the report this large map was prepared. The map is an illustration of the expedition of 1845-46. Fremont described the map “The map has been constructed expressly to exhibit the two countries of Oregon and the Alta California together. It is believed to be the most correct that has appeared of either of them; and it is certainly the only one that shows the structure and configuration of the interior of Upper California.” Wheat states that “More than any other persons, John Charles Fremont and Charles Preuss dominate the cartography of the American West during the three years before the Gold Rush brought a human tide surging into that land which had so long lain beyond the ken of most Americans” (Wheat, Mapping of the Transmississippi West, 523).

The map is a remarkable large scale map of the American west before the onslaught of the Gold Rush. It extends from the 105th Meridian westwards to the Pacific Coast. The northern and southern borders are coloured green, as are the borders between Oregon and California and the eastern boundary of the Rocky Mountains, the South Pass and Sierra Madre. Across the top is an profile of the elevation of the route from the South Pass to San Francisco. Of particular note on the map is the mention on the Plumas (Feather) and American Rivers of ‘El Dorado’ or Gold Region, one of the earliest references to the discovery of gold in California. It became the model for many of the ensuing California Gold Rush maps. The nearby Lake Bonpland is Lake Tahoe. Other interesting references are one to the ‘Golden Gate’ at the entrance to the Bay of San Francisco and a note identifying the location of Mormon settlements for the first time. Despite its obvious geographical advances the political scene was not left behind. Indeed the very latest from the recent boundary disputes is illustrated. ‘Oregon Territory’ was only established by Congress in August 1848 but is clearly delineated, as are the boundaries with Mexico only just settled by the Treaty of Guadalupe Hidalgo.

Wheat effuses on the map illustrating it and devoting eight pages to its description. Howes debates the origin of the map stating that it was “not issued in all copies, if any, [Fremont’s Geographical Memoir] but [was] intended to accompany the pamphlet” (Howes F366). Schwartz calls it an “epochal” map and states that the map is the “most accurate general map of the Far West for its time.” A fine copy of this large and increasingly rare map from that report. Cohen Mapping the West p. 152-3; Goss, J. (N. Amer) 177; Howes, W. F366; Schwartz & Ehrenberg pl. 171; Storm, C. 1429; Streeter (Sale) 2524; Wagner & Camp 150; Wheat, C.I. (TM) 559, illus.