It was generally understood by 1970 that the US didn't hold enough gold to fulfill the promise. You as a normal person couldn't go to any bank and get 1oz of g

It was generally understood by 1970 that the US didn't hold enough gold to fulfill the promise. You as a normal person couldn't go to any bank and get 1oz of gold though, only other countries could do that and they didn't in large amounts and so it worked out despite there not being enough gold in the US. In the 1800s 1oz of gold was tradable for $20. The $35 figure was already accounting for some inflation despite the backing (I don't recall the year it changed, but sometime in the 1930s seems reasonable) $1 used to be tradable for 1oz of silver. since silver and gold have different supplies though sometimes you could (in the 1800s) make a lot of money from this.