We were on the gold standard (Bretton Woods system) that was established after WWII until Nixon ended it in 1971 when countries started to demand gold as payment from the Federal Reserve Banks instead of US Dollars because they didn't believe America could pay its debt due to spending more than it collected in taxes, and they were correct. We've been deficit spending ever since to pay for all of our toys. We owe more now than at any other time in our history. No country that has gone to a fiat currency system at any time in world history has lasted. It was probably the worst thing that Nixon did to this country, but we only talk about the other bad thing he did.
https://www.federalreservehistory.org/essays/gold-convertibi...