<P> "The Star - Spangled Banner" is the national anthem of the United States . The lyrics come from Defence of Fort M'Henry, a poem written on September 14, 1814, by the then 35 - year - old lawyer and amateur poet Francis Scott Key after witnessing the bombardment of Fort McHenry by British ships of the Royal Navy in Baltimore Harbor during the Battle of Baltimore in the War of 1812 . Key was inspired by the large U.S. flag, with 15 stars and 15 stripes, known as the Star - Spangled Banner, flying triumphantly above the fort during the U.S. victory . </P> <P> The poem was set to the tune of a popular British song written by John Stafford Smith for the Anacreontic Society, a men's social club in London . "To Anacreon in Heaven" (or "The Anacreontic Song"), with various lyrics, was already popular in the United States . Set to Key's poem and renamed "The Star - Spangled Banner", it soon became a well - known U.S. patriotic song . With a range of 19 semitones, it is known for being very difficult to sing . Although the poem has four stanzas, only the first is commonly sung today . </P> <P> "The Star - Spangled Banner" was recognized for official use by the United States Navy in 1889, and by U.S. President Woodrow Wilson in 1916, and was made the national anthem by a congressional resolution on March 3, 1931 (46 Stat. 1508, codified at 36 U.S.C. § 301), which was signed by President Herbert Hoover . </P> <P> Before 1931, other songs served as the hymns of U.S. officialdom . "Hail, Columbia" served this purpose at official functions for most of the 19th century . "My Country,' Tis of Thee", whose melody is identical to "God Save the Queen", the United Kingdom's national anthem, also served as a de facto national anthem . Following the War of 1812 and subsequent U.S. wars, other songs emerged to compete for popularity at public events, among them "America the Beautiful". </P>

When did star spangled banner became the national anthem