Although more than sixty years have passed since President John F. Kennedy was assassinated in downtown Dallas, visitors still come daily to Dealey Plaza to pay their respects (or discuss conspiracy theories). They take tours—on foot, on Segways, by trolley, in electric cruisers, and even in a restored 1963 midnight-blue Lincoln Continental convertible. And each year, about 350,000 pay a fee ($25 for adults) to enter the Sixth Floor Museum, located in the former Texas School Book Depository, to see the “sniper’s perch” from which Lee Harvey Oswald fired the fatal shots. Other must-sees include the FBI’s 3-D model of Dealey used during the Warren Commission investigation, the Jack Ruby trial transcripts, and Lee Harvey Oswald’s wedding ring.“That year, 1963, unites generations of Dallasites,” says…