We speak with Mark Clague, a musicologist and music professor at the University of Michigan, who is widely regarded as one of the country's leading authorities on the Star Spangled Banner. His book "O Say Can Gou Hear: A Cultural Biography of the Star Spangled Banner," traces the roots of our national anthem and chronicles the ways in which it has been used over the years. Clague also gives extensive background information about Francis Scott Key, who penned the lyrics - and also discusses some of the most iconic performances of the anthem.