Bottom row: Prominent design elements used on the front of $5 and $20 Demand Notes (located respectively under their denomination); pictured in the middle is the front of a $10 Demand Note with prominent design elements listed
A Demand Note is a type of United States paper money that was issued from August 1861 to April 1862 during the American Civil War in denominations of 5, 10, and 20 US$. Demand Notes were the first issue of paper money by the United States that achieved wide circulation. The U.S. government placed Demand Notes into circulation by using them to pay expenses incurred during the Civil War including the salaries of its workers and military personnel.
Because of the distinctive green ink on their reverse, and because state-chartered bank and Confederate notes of the day typically had blank reverse, the Demand Notes were nicknamed "greenbacks", a name later inherited by United States Notes and Federal Reserve Notes. The obverse of the Demand Notes contained familiar elements such as the images of a bald eagle, Abraham Lincoln, and Alexander Hamilton, though the portraits used on Demand Notes are different from the ones seen on U.S. currency today.
When Demand Notes were discontinued, their successors, the United States Notes, could not be used to pay import duties, a large part of the U.S. federal tax base at the time, and thus Demand Notes took precedence. As a result, most Demand Notes were redeemed, though the few remaining Demand Notes are the oldest valid currency in the United States today.