Because Congress made a law in 1931 declaring it to be so.
The Star Spangled Banner was only one of several equally-prominent US patriotic songs until 1889, when Secretary of the Navy Benjamin F. Tracy issued a general order that it be played at the raising of the flag on US Naval ships and shore stations. Then in 1916 President Woodrow Wilson ordered that it be played "on appropriate occasions" throughout the US Military. But only in 1931 was it officially elevated over other patriotic tunes for civilian use.
The custom of playing The Star Spangled Banner before every Baseball game started during World War Two.
The Star Spangled Banner is the US national anthem.
The national anthem of the USA is "The Star-Spangled Banner."
The Star Spangled Banner
The "Star-Spangled Banner" was adopted as the national anthem of the United States in 1931.
9 decades the star spangled banner has been in the USA.
On March 3, 1931, after 40 previous attempts failed, a measure passed Congress and was signed into law that formally designated “The Star-Spangled Banner” as the national anthem of the United States.
The Star Spangled Banner.
The Star Spangled Banner is the United States' national anthem.
there wasn't one before its just the star spangled banner
duuhhh! star spangled banner!
The Star Spangled Banner
The Star-Spangled Banner.