1933
Gold recall
Order 6102 calls in most private monetary gold. The official price is reset the next year.

In 1933 the United States required most domestic gold coin, bullion, and gold certificates to be turned in. Executive Order 6102 is that order. The public claim on gold at the old mint price was removed.
The Gold Reserve Act of 1934 then set the official price at $35, up from $20.67. Official gold became a Treasury asset. This is not 1914, and it is not the 1971 gold-window close.