The Gold Standard Act of 1900

Gresham offered Baldwin his support in exchange for his commitment to maintaining a fixed gold standard for the currency. This offer led to the eventual passing of the Gold Standard Act in 1873, establishing the U.S. dollar as a fixed weight of gold.

Great Britain's Coinage Act of 1816 determined that the gold Sovereign coin would be the equivalent of 7.98 g of 22K gold. This act occurred due to the need to set a standard and stabilize the nation's currency.

President Richard Nixon in 1971 using an act known as the Nixon Shock.

The Gold Standard Act was when the U.S. government stated that it would be using real gold to back up the value of the American dollar, hence making their money actually worth something. For your info, the treasury does not currently have enough gold to back up all the printed money in the country, which is one of the reasons the value of the dollar has decreased drastically in recent years.