The 37^th Congress (1861–1863) faced a financial crisis in 1862, as spiraling costs of war rapidly depleted the Union’s reserves of gold and silver coin, the only legal tender of the United States. After intense debate, Congress authorized the issuance of paper U.S. Notes (popularly called “greenbacks”), declaring them lawful money for all payments except interest on public debt and import duties. The Legal Tender Act, intended as an emergency measure, dramatically extended federal power and changed the nation’s monetary standard.