Schulke formed a bond with civil rights activist Martin Luther King, Jr. after an all-night conversation in 1958, and began photographing him. King invited Schulke to photograph secret planning meetings of the Southern Christian Leadership Conference, though not all of the activists trusted him being there. He also photographed the 1963 March on Washington and the 1965 Selma to Montgomery March. They traveled together until King's death in 1968, which upset Schulke so much that he stopped covering the civil rights movement and began to work on more commercial projects. In all, he took around 11,000 photographs of King, including some of his funeral.