Has the US ever been on a gold standard? What year did it end?

I think it was, and it ended in 1971. Up to that point, you could argue that using dollars was a payment rail on top of gold. That's how I use bitcoin today. The dollar is just a payment rail to me.

I pay with bitcoin directly to anyone that accepts it. I buy beef, wine, coffee, soap, etc. with bitcoin regularly. For everyone else, its credit cards.