Each November, as we approach Thanksgiving, the echo of President John F. Kennedy’s assassination in Dallas 59 years ago still manages to creep in around the edges of the holiday. Those old enough to have experienced the tumult surrounding the president’s death through the emerging medium of television tend to recall the grief and the anger of those awful days as if they had themselves watched the open car roll past the book depository. The memory keepers are an aging group whose numbers get smaller with every passing year. But tucked away in the archives of SMU’s DeGolyer Library, the...