"The Star-Spangled Banner" was made the national anthem by a congressional resolution on March 3, 1931, which was signed by President Herbert Hoover.
The lyrics come a poem written in 1814 by the 35-year-old lawyer and amateur poet, Francis Scott Key, after witnessing the bombardment of Fort McHenry during the War of 1812.
The poem was later set to the tune of a popular British pub song and renamed "The Star-Spangled Banner." It was recognized for official use by the Navy in 1889, and by President Woodrow Wilson in 1916.
With a range of one and a half octaves, it is known for being incredibly difficult to sing. Although the song has four stanzas, only the first is commonly sung today.
(The fourth stanza includes the line "And this be our motto: In God is our Trust," which the United States adopted as its national motto in 1956.)
The singable "My Country, 'Tis of Thee" (whose melody is identical to Great Britain's "God Save the Queen/King") served as one of our many anthems before the adoption of "The Star-Spangled Banner."