Principal Gold Producing Districts of the United States by A. H. Koschmann and M. H. Bergendahl (USGS) 1968 USGS Professional Paper 610, 30.66 MB pdf file, 290 pages A description of the geology, mining history, and production of the major gold-mining districts in 21 states. Gold Panning, Sluicing, Dredging, Drywashing Forum