when was the us dollar backed by silver
History of the United States dollar United States silver certificates were a type of representative money printed from 1878 to 1964 in the United States as part of its circulation of paper currency.[16] They were produced in response to silver agitation by citizens who were angered by the Fourth Coinage Act, and were used alongside the gold-based dollar notes. The silver certificates were initially redeemable in the same face value of silver dollar coins, and later in raw silver bullion.
Fiat money The Bretton Woods system collapsed in what became known as the Nixon Shock. This was a series of economic measures taken by United States President Richard Nixon in 1971, including unilaterally canceling the direct convertibility of the United States dollar to gold. Since then, a system of national fiat monies has been used globally, with freely floating exchange rates between the major currencies.[27]