From 1792, when the Mint Act was passed, the dollar was pegged to silver at 371.25 grains (24.056 g), or 24.75 grains (1.604 g) of gold. Many historians[who?] erroneously assume gold was standardized at a fixed rate in parity with silver, however there is no evidence of Congress making this law. This has to do with Alexander Hamilton's suggestion to Congress of a fixed 15:1 ratio of silver to gold, respectively. The gold coins that were minted however, were not given any denomination whatsoever and traded for a market value relative to the Congressional standard of the silver dollar. 1834 saw a shift in the gold standard to 23.2 grains (1.50 g), followed by a slight adjustment to 23.22 grains (1.505 g) in 1837 (16:1 ratio).
In 1862, paper money was issued without the backing of precious metals, due to the Civil War. Silver and gold coins continued to be issued and in 1878 the link between paper money and coins was reinstated. This disconnection from gold and silver backing also occurred during the War of 1812. The use of paper money not backed by precious metals had also occurred under the Articles of Confederation from 1777 to 1788. With no solid backing and being easily counterfeited, the continentals quickly lost their value, giving rise to the phrase "not worth a continental". This was a primary reason for the "No state shall... make any thing but gold and silver coin a tender in payment of debts" clause in article 1, section 10 of the United States Constitution.
The Gold Standard Act of 1900 abandoned the bimetallic standard and defined the dollar as 23.22 grains (1.505 g) of gold, equivalent to setting the price of 1 troy ounce of gold at $20.67. Silver coins continued to be issued for circulation until 1964, when all silver was removed from dimes and quarters, and the half dollar was reduced to 40% silver. Silver half dollars were last issued for circulation in 1969.
Gold coins were confiscated in 1933 and the gold standard was changed to 13.71 grains (0.888 g), equivalent to setting the price of 1 troy ounce of gold at $35. This standard persisted until 1968. Between 1968 and 1975, a variety of pegs to gold were put in place. The price was at $42.22 per ounce before August 15, 1971 saw the U.S. dollar freely float on currency markets.
According to the Bureau of Engraving and Printing, the largest note it ever printed was the $100,000 Gold Certificate, Series 1934. These notes were printed from December 18, 1934 through January 9, 1935, and were issued by the Treasurer of the United States to Federal Reserve Banks only against an equal amount of gold bullion held by the Treasury. These notes were used for transactions between Federal Reserve Banks and were not circulated among the general public.