Greenbacks were paper currency issued by the Union government from 1862 to 1865, during the American Civil War. Issued in denominations of 1, 2, 5, 10, 20, 50, 100, 500 and 1000 dollars, they were legal tender but were not backed by gold or silver. The obverse of the banknotes was printed in green, black and red, while the reverse was printed in green, giving the notes their popular name of "greenbacks". They were signed by Lucius E. Chittenden, Register of the Treasury, and Francis E. Spinner, Treasurer of the United States.
This picture shows a twenty-dollar greenback issued in 1863, featuring a personification of Liberty bearing a sword and a shield on the obverse. This banknote is part of the National Numismatic Collection at the Smithsonian Institution's National Museum of American History.
Other denominations: $1, $2, $5, $10, $50, $100, $500, $1000Banknote design credit: American Bank Note Company; photographed by Andrew Shiva