A fine example of the second issue one of the most important maps ever produced of the American West issued in the nineteenth century, a map Carl Wheat calls “magnificent.” (p. 49).  John C. Frémont popularly known as the “Pathfinder,” was instrumental in opening the American West.   Between 1842 and 1844, Frémont explored along the Oregon Trail to California, then heading south, returned east through the Great Basin, thus doing a circuit which for the first time established the basic outlines of the Western part of what would become, in just a few years, the western part of the United States.

In 1845, Frémont was sent out again, in part because of the conflict between the U.S. and Mexico which would lead the next year to war.  Frémont arrived in California when local ferment led to an American rebellion which soon became part of the wider Mexican War.  Frémont was appointed the first Governor of California, but soon became embroiled in a conflict with the military commander of California, General Stephen W. Kearny.  This led to Frémont being sent back east under arrest and to his eventual court-martial and dismissal from the army.

Despite the personal failure of this 1845-46 expedition, the resulting map that Charles Preuss produced based on Frémont’s surveys is a landmark, one of the most important maps of the American West.   This is the second issue of Frémont’s map, which shows just the old Mexican territory of Upper California.  Drawing on the earlier Frémont/Preuss map of the region from 1845, this map is corrected and filled in considerably, making it by far the best map of the region to date.  The importance of Frémont’s map is indicated by the fact that Carl Wheat gave more space to the description of this map than to any other.