The United States dollar was the primary currency in the 1920s. During this time, the dollar was referred to as the "hard dollar" because it was backed by gold and other precious metals, as opposed to a fiat currency that is not backed by any physical assets. The gold standard was maintained by the United States until 1933, when President Franklin D. Roosevelt devalued the dollar by over 40% in an effort to stimulate the economy during the Great Depression.