Amazingly, Mary Moorman took this Polaroid shot of the limousine a split second before Kennedy's head exploded from a bullet impact.  The impact sent Kennedy hurling back and to his left, meaning that the shot came from the right and front.  Obviously,  the right and front means the area of the picket fence on the top of the grassy knoll in the background, not from the 6th floor of the Texas School Book Depository.  This was the tail-end of the motorcade route, about a quarter mile from the Stemmons Freeway the motorcade was to turn on to,  and few people were in the area.  Notice the clear shot available from behind the picket fence.