Frémont's important and highly influential map of the west, executed with the assistance of Charles Preuss, issued in his Report of the Exploring Expedition to the Rocky Mountains in the Year 1842, and to Oregon and North California in the Years 1843-'44. Wheat describes the map at great length, and attaches great significance to it: "The year 1845, however, though otherwise somewhat cartographically barren, because of a single event is in fact one of the towering years in the story of Western Cartography. In that year John C. Frémont's report of his journey to Oregon and California in 1843-44 was published. This report and the Frémont (Preuss) map which accompanied it, changed the entire picture of the West, and made a lasting contribution to cartography...." Graff 1436; Howes F370; Wagner-Camp 115; Wheat Transmississippi 497.