Walter K. asks: Why is U.S. paper money mostly green when other countries use different colors for different bills? In Article I of the U.S. Constitution, ratified on June 21, 1788, Congress was granted the power to “coin money” and “regulate” its value, but not to issue paper money. The result of the near complete devaluation of the paper money printed to fund the Revolution (bills called “continentals” since they were issued by the Continental Congress, see: A Capital Idea- How a Pile of Unpaid Bills Led to Washington, D.C.), many delegates of the Constitutional Convention simply had lost faith in the efficacy of paper money, and made no provision for it. Producing bills of various designs and values, by the time the U.S. Congress had gotten around to issuing its own paper money, approximately 8,000 different private entities within the United States had already produced some form of paper currency. This all brings us back to green money.