Designed in part by Robert Mills in 1836, the United States Treasury building served as the Union’s financial command center during the Civil War. Between 1861 and 1865, Secretary of the Treasury Salmon P. Chase raised the unprecedented sum of $2.7 billion to finance the government and the war by issuing bonds, instituting internal revenue taxes, printing paper money called greenbacks, and creating the first personal income tax in the United States. He also developed the nation’s first system of national banks to provide financial stability, a network that remained in place until the present Federal Reserve System was devised early in the 20th century. Throughout the war, the building bustled with activity: the 5th Massachusetts camped there and cooked in the courtyard, the basement became a bunker for the president and his cabinet in case of Confederate attack, and the federal government hired large numbers of women there for the first time. These lady clerks trimmed by hand the huge sheets of paper greenbacks invented by Chase. In 1863, the building also became the setting for an experiment devised by President Lincoln, in which all loyal slave owners in the District of Columbia were paid to free their slaves, a model never carried out anywhere else in the country.
