<P> Greenbacks were paper currency (printed in green on the back) issued by the United States during the American Civil War . They were in two forms: Demand Notes, issued in 1861--1862, and United States Notes issued in 1862--1865 . They were legal tender by law, but were not backed by gold or silver, only the credibility of the U.S. government . </P> <P> Before the Civil War, the only money issued by the United States was gold and silver coins, and only such coins ("specie") were legal tender; that is, payment in that form had to be accepted . </P>

Legal tender printed by the union during the civil war that was not backed by gold or silver