Sketch of General Riley's Route through the Mining Districts July and Aug. 1849

Item Details

[Washington, D.C.], [U.S. Congress]

Lithographed map (21x19½"), plus margins. Fold lines, as issued. Light general wear; a very good map.

This map, created by U.S. Army Topographical Engineer Lt. George Horatio Derby, documents the reconnaissance tour of Brig. Gen. Bennet Riley, the last Military Governor of California, through the early Gold Rush mining regions of Northern California. Produced from Derby's original field sketches in the office of the 10th Military Department, it was published as an appendix to Riley's official report dated September 20, 1849, and included in U.S. Senate and House documents in 1850. The map traces Riley's daily route (marked with dates from July 10 to August 20, 1849) from Monterey northward via San Francisco, across the Central Valley, and into the mining districts along rivers like the American, Cosumnes, Mokelumne, Calaveras, Stanislaus, Tuolumne, Merced, and Mariposa. A cornerstone of Gold Rush cartography, providing the first printed names and locations of central Sierra foothill diggings—essential for prospectors and historians. (Wheat, Maps of the Gold Region #79)