A United States Note, also known as a Legal Tender Note, is a type of paper money that was issued from 1862 to 1971 in the U.S. Having been current for over 100 years, they were issued for longer than any other form of U.S. paper money. They were known popularly as "greenbacks" in their heyday, a name inherited from the earlier greenbacks, the Demand Notes, that they replaced in 1862. Often called Legal Tender Notes, they were called United States Notes by the First Legal Tender Act, which authorized them as a form of fiat currency. During the 1860s the so-called second obligation on the reverse of the notes stated:

They were originally issued directly into circulation by the U.S. Treasury to pay expenses incurred by the Union during the American Civil War. Over the next century, the legislation governing these notes was modified many times and numerous versions were issued by the Treasury.