This paper provides a new test for whether different-currency assets are imperfect substitutes. The test exploits that under floating rates, changing public currency demand has no direct effect on monetary fundamentals, current or future. Price effects from imperfect substitutability are clearly...

U.S. currency has long been a desirable store of value and medium of exchange in times and places where local currency or bank deposits are inferior in one or more respects. Indeed, as noted in earlier work, a substantial share of U.S. currency circulates outside the United States. Although...