1920, November – The New Idria Quicksilver Mining Company closes because of falling price of quicksilver and the company goes into receivership.
1923, April – New Idria opens again as New Idria Quicksilver Mines, Incorporated.
1924 – Electricity came from the Coast Valleys Gas and Electric Company's fifty-six mile long power line, which extended from King City to the mines.
1930 – New Idria installs an underground conveyor system which is the first of its kind in the United States.
1936, June – The mine is visited by former-president Herbert Hoover, who had a degree in mining engineering from Stanford University and had worked as a mining engineer before he became president of the United States.
1939 – The New Idria Quicksilver Mining Company constructs a baseball field on the property. The field even has lights so Idria residents could play night games. It is thought by many people to be the first lighted baseball field in California.
