In the summer of 1861, the United States embarked on its first widespread use of paper money: the Demand Notes of 1861. Although their convertibility into gold ended at the end of that year, they remained acceptable for tariff payment at a par with gold coin while they were gradually replaced with paper money that did not share this provision, the Greenbacks. We present daily observations of exchange rates between the Notes, Greenbacks, and gold for the extended period during which they simultaneously circulated. These exchange rates substantiate our revisionist notion that the Notes were replaced because the tariff provision prevented them from generating sufficient seigniorage for wartime needs. (JEL E42, N12, N22)