The legend on the 1904 map of Calaveras County says it all: 

"Official Map of Calaveras County, California, compiled from United States Official Surveys; Mines and Mining Claims as shown by records of County; Mother Lode as shown by State Mineralogist; Wagon Roads and Trails as shown by United States survey; Reservoirs, Water Ditches from private surveys; Supervisor, School, and road District Boundaries. Published by J.J. Agostini, San Andreas, Ca. 1904. Scale: one half inch to one mile." 

Click on the link below and brouse the map in detail.  (in Windows, open in Adobe Photoshop).