How was the national anthem selected?

The national anthem of the United States, "The Star-Spangled Banner," was officially adopted in 1931, although its origins date back to 1814 when Francis Scott Key wrote the lyrics after witnessing the bombardment of Fort McHenry during the War of 1812. The melody is based on a popular British song by John Stafford Smith. Prior to its official status, the song had gained popularity and was often performed at public events. Its adoption was part of a broader movement to establish a sense of national identity and pride.