Congress made “The Star-Spangled Banner” the official U.S. national anthem in 1931.
The song began as a poem called “Defence of Fort M'Henry,” written by Francis Scott Key after he witnessed the British bombardment of Fort McHenry during the War of 1812. Key saw the American flag still flying over the fort after the battle and turned the experience into four stanzas.
The poem was set to the melody of “The Anacreontic Song,” a British tune composed by John Stafford Smith. It became increasingly popular as a patriotic song during the nineteenth century, but it did not immediately have legal status as the national anthem.
Congress passed a joint resolution on March 3, 1931, and President Herbert Hoover signed it on March 4. The song is sometimes confused with “America the Beautiful” or “God Bless America,” both widely performed patriotic songs that have never replaced it as the official anthem.