At the risk of having your (ok, my) head explode, lets savor some numbers, past and present and hope we don't injure ourselves.
1. Presently there will be, let's take Dave Webb's estimate, only about one gold explorer in a hundred that will become a producing mine.
2. There are currently between one thousand and two thousand explorers now attempting to become miners.
3. In 1940 there were 9,000 producing gold mines in the USA (Ian Gordon, citing figures from the US Bureau of Mine Stats.)
4. So, here's where we are in danger of mentally short circuiting.
My Question: What might have been the number of USA explorers in the 1930's that never made it into production? Does about 90,000 seem reasonable, or would it have been more like 900,000?
Or, were things so different then, that an explorer was defined by anyone with a beard, pick and pan?
Just musing along with my morning coffee?
Baires