Principal Gold Producing Districts of the United States
The 25 leading districts have produced about half the gold mined in the United States, and the 508 districts that are described account for roughly 90 to 95 percent. In general, gold is derived from three types of ore: (1) ore in which gold is the principal metal of value, (2) basemetal ore which yields gold as a byproduct, and (3) placers.