Five decades later, the assassination of John F. Kennedy remains one of the few utterly signal events from the second half of the 20th century. Other moments — some thrilling (the moon landing, the fall of the Berlin Wall), others horrifying (the killings of Martin Luther King Jr. and Robert Kennedy, the Challenger explosion) — have secured their places in the history books and, even more indelibly, in the memories of those who witnessed them. But nothing in the latter part of “the American century” defined an era as profoundly as those rifle shots that split the warm Dallas air on November 22, 1963, and the sudden death of the 46-year-old president.  There was Camelot — a media construct, of course, but a rarity in that it actually resonated with so many people, everywhere — and then there was the somber, profoundly uncertain period after Camelot. For countless millions in America and around the globe who lived through the near-surreal transition, the days and weeks after JFK’s assassination felt like a chilling, restless pause: a moment so charged with unease that even reflection, or taking stock, seemed impossible.  Here, on the 45th anniversary of JFK’s March 1967 reinterment, when his remains were moved from his initial resting place to the permanent grave site and memorial at Arlington, LIFE.com offers a gallery of photographs (some of them never before published) from the deeply fraught funeral held mere days after Kennedy was killed. While both ceremonies — the state funeral in ’63, and the reinterment three-and-a-half years later — were marked by sorrow, the rawness of the emotion evident in 1963 is still striking, and rending, today.  “A woman knelt and gently kissed the flag,” LIFE magazine reported of the scene as JFK’s casket lay in state for two days after his assassination. “A little girl’s hand tenderly fumbled under the flag to reach closer. Thus, in a privacy open to all the world, John F. Kennedy’s wife and daughter touched at a barrier that no mortal ever can pass again.”  The next day, Kennedy’s body was taken “from the proudly impassive care of his honor guard” and was carried from the Capitol rotunda to Arlington.  “By a tradition that is as old as Genghis Khan,” LIFE noted, “a riderless horse followed” the flag-draped casket, “carrying empty boots reversed in the stirrups in token that the warrior would not mount again…. Through all this mournful splendor Jacqueline Kennedy marched enfolded in courage and a regal dignity. Then at midnight she came back again, in loneliness, to lay some flowers on her husband’s grave.”
On the anniversary of JFK's 1967 reinterment in Arlington Cemetery, LIFE presents rare and unpublished photos from his state funeral in 1963, mere days after the assassination that shook the world.