My favorite use of the US dollar was riding on the train between London and York (England). Their dining car would accept pounds (obviously), but also euros and US dollars. So here we are, riding on a train in England, buying a Belgian beer and paying for it with US dollars (the exchange rate was close to the bank’s). It didn’t seem to faze the dining car attendant.
I toured a Federal Reserve bank not long ago and learned that an estimated two-thirds of all U.S. paper currency is actually outside of the U.S. Blew my mind.
Technically, it’s illegal for foreigners to enter or leave India with rupees and Indians can only move 5000 (~$110) at a time.