Many of Martin Luther King. Jr.'s speeches are well-known, such as his famous "I Have a Dream" speech (which brings to mind a memory of my maternal grandmother Margaret Ann (Schneider) Boe). But several years ago, a tape was discovered in the archives of the New School, a university in New York City where two of my relatives are members of the faculty. On 6 February 1964, King gave the inaugural speech of a lecture series, "The American Race Crisis." Although a recording of the speech itself has not been found, an audiotape of a 15-minute question-and-answer session was discovered. Experts had not previously known about the speech, in which King compared the situation of African-Americans to the "untouchable" castes in India. This was a significant discovery, and since it took place at an institution where two family members were working, there is a bit of a family history connection.
Source: El Naggar, Mona. Found After Decades, a Forgotten Tape of King 'Thinking on His Feet'. 22 August 2013.