On April 9, 1939, Black contralto Marian Anderson stood on a stage before the Lincoln Memorial in Washington, D.C. Facing a crowd of 75,000 people on the National Mall, she began to sing "America, My Country 'Tis of Thee." From the very first note, her sweet and powerful voice took flight--soaring over the National Mall and floating out of radios across the nation. But why was Anderson singing outside on that chilly day, and what was the enduring...