The U.S. Flag has gone through many changes before it was decided the stripes would represent the original 13 Colonies and the stars would represent each of the states, to date there are 50 on a field of blue.
One such flag was the 15 Star, 15 Stripe U.S. Flag. The 15 Star, 15 Stripe Flag came to be known as the Star Spangled Banner. It was this flag that flew at Fort McHenry during the War of 1812. After the long night of bombardment Francis Scott Key looked out over the harbor form the prison ship he was on, saw the flag still flying and wrote the words to what became the National Anthem of the United States of America.
There are 2 such examples of the Star Spangled Banner in Sioux City. One flies along the river front and the other at the Floyd Monument:
