To commemorate the man and his legacy, here is the full text of his landmark speech.
Only one other state in America commemorates the births of both men on the same day.
Martin Luther King III talked to Newsweek.
Hefner's magazine was a platform for African-American leaders, including Martin Luther King Jr., during the 1960s civil rights struggle.
Photos from the April 15, 1968 issue of Newsweek provide a behind-the-scenes look at the nationwide riots following Martin Luther King Jr.'s assassination.