ニクソン・ショック
The Gold Reserve Act of 1934 made gold clauses unenforceable and authorized the President to establish the gold value of the dollar by proclamation. Immediately following its passage, Roosevelt changed the statutory price of gold from $20.67 to $35 per ounce, thereby devaluing the US dollar, which was based on gold. That price remained in effect until August 15, 1971, when President Richard Nixon announced that the US would no longer convert dollars to gold at a fixed value, thus abandoning the gold standard for foreign exchange (see Nixon Shock).