1. The dollar itself was created two centuries before the US left the gold standard. "Created" being the operative word. Created by Congress because America needed its own national currency.
2. Anyone who dug some gold up in their backyard was creating money when we were on the gold standard.
3. In 1862 paper money became legal tender in the USA without any guaranteed convertibility to any metal; that remained the situation until 1879. I.e. the government simply created money.
4. On January 31, 1934, the US dollar was devalued from $20.67 per gold ounce to $34. In other words money was created by an act of Congress.
Or to sum all that up for you: at a minimum Congress has always had the power to create money. All the metallic standards ever conceived of have been arbitrarily decided and governments have always had the ability to change the standard at will to create more money.