Sketch of General Riley's Route through the Mining Districts July and Aug. 1849; From the Original Sketch by Lt. Derby in the Office of the 10th Military Department by J Mc. Hollingsworth, Asst. [Ackermann's Lithograph] [31st Congress, 1st Session, House Ex. Doc. No. 17, Serial 573, Message From the President (Zachary Taylor), December 31, 1849]

Washington City: Government Printing Office, 1850. First State. Very Good Plus. [Neatline 20.5x19.25in, Sheet 23.25x21in]; Title in lower left corner with stylized lettering; A lithograph map of Northern California from just south of Monterey to just north of Sacramento and from the Pacific Ocean to the Sierra foothills; Showing General Bennet Riley's route through the mining districts with dates visiting the mining camps in the Sierra foothills; The map is printed on thin paper and laid flat with fold creases evident, outer vertical right neatline trimmed, archival repaired closed tear at top right edge. a few light foxing spots in upper and lower right. [Wheat Maps 79, Kurutz 106b, Wagner-Camp 179b, Zamorano80 #14]. In 1850, this was an important and highly desirable map of California Gold Rush diggings. The map was part of the Senate and House reports of Brev Brig Gen. Bennet Riley dated at Monterey on September 20, 1849 entitled "Report of a Reconnaissance of a Portion of the San Joaquin and Sacramento Valleys". (From Wheat). The map provides the earliest names and location of the mining camps and diggings in the central Sierra foothills along the American, Cosumne, Dry Creek, Mokelumne, Calaveras, Stanislaus, Tuolumne, Merced, Lost Creek, Maraposa [sic] and King rivers of the Central Valley draining to the San Joaquin river. The more populated camps were Mormon Island (mis-spelled Mormont), Coloma (mislabeled Colluma), Curtis, Sullivan's, Jamestown, Woods, Maj. Miller's and Sonoran Camps. Lt. Derby provides topographical and travel conditions along the routes with dates and details in the geography, terrain and communities.

General Bennet Riley (1787-1853) was the 6th and last Military Governor of California in 1849. He ordered four surveys of California to be led by Lt. George Derby.

George Horatio Derby (1823-1861) also known as John Phoenix or John P. Squibob or just Squibob, was an 1846 West Point graduate. As a Lt. in the U.S. Army Corps of Topographical Engineers, he , participated in the Mexican-American war and was assigned to California in 1849. Under General Riley, Military Governor, he explored and mapped of California and Oregon during the early years of the Gold Rush. To supplement his army income, he wrote humorous articles and this book on the irreverent side of California life.

The purpose of the 1849 journey was to identify existing settlements and mining camps and determine locations of strategic military supply routes and posts to "... afford protection for and from the Indians and keep the peace among the gold miners." [William H. Goetzmann, Army Exploration in the American West 1803-1863, Yale University Press, 1959, p.255]. This map relates to another important early map of the Sacramento Valley surveyed in September and October 1849 from north of Sacramento City to the Butte River (the second survey ordered by General Riley). A third survey was ordered by General Riley in 1850 to survey the southern Tulares Valley in April and May of 1850. The Map of Reconnaissance of the Tulares Valley was included in the Senate Exec. Doc. No. 110 August 24, 1852. (Inventory #: 14303)