Greenback officially refers to the paper currency that was issued by the United States during the American Civil War. However, nowadays, greenback is American slang for different denominations of dollar bills.

Two types of notes that are called greenback are the United States note and the demand note.

The Demand Note is a paper bill that was issued in the United States from August 1861 to 1862. Demand notes were issued in 5, 10, and 20 dollar denominations. Demand notes were printed out by the government to pay for the Civil War, including wages of workers and the military, as well as payment for guns and ammunition. The money got the nickname greenbacks due to the predominantly green and black color used.

The United States note is a paper bill that came along after the Demand Note and lasted from 1862 to 1971. It was first printed out after President Lincoln signed the First Legal Tender Act in 1862. Aside from being a product of the First Legal Tender Act, the United States Note is also called Legal Tender Note because written on the notes are the words “”This Note is a Legal Tender”. Unlike the Demand Note, which was issued only in 5, 10, and 20 dollar denominations, the United States Note were issued in 50, 100, 500, and 1000 dollar denominations.

Although no new United States Notes weere printed out after 1971, they were still used, until 1996 when the US Treasury announced that its stock of $100 United States Notes had been destroyed. Nowadays, the United States Notes have been replaced by Federal Reserve Notes.