1) when the US was on the gold standard this was before the US was the number 1 economy in the world and the USD was the number 1 international reserve currency. The gold standard was stopped prior to this.
You might want to check your info. Dollars were convertible to gold until 1971.
Thanks for clarifying my error, but I must clarify your error as well:
US became the top economy in around 1920s: "The United States has been the world's largest national economy since at least the 1920s"
http://en.wikipedia.org/wiki/Economy_of_the_United_StatesUS came off the gold standard in 1933: " On June 5, 1933, the United States went off the gold standard, a monetary system in which currency is backed by gold, when Congress enacted a joint resolution nullifying the right of creditors to demand payment in gold."
http://www.history.com/this-day-in-history/fdr-takes-united-states-off-gold-standardSo I was incorrect in saying that gold standard was stopped prior to US taking #1 globally. Actually US took #1 a decade before.
That being said, the main idea is that being off the gold standard has been optimal.