AP Explains: National anthem is icon of patriotism, protest

San Francisco 49ers quarterback Colin Kaepernick's recent decision to not stand during the national anthem as a way of protesting police killings of unarmed black men has drawn support and scorn far beyond sports. The Associated Press explains how "The Star-Spangled Banner" became a ritual of American public life, its complicated racial origins and how the song has been used as a form of political resistance.