President John F. Kennedy and first lady Jacqueline Bouvier Kennedy arrive at Love Field in Dallas, Texas less than an hour before his assassination on Nov. 22, 1963. (Bettmann/CORBIS) #

President Kennedy and Jacqueline Kennedy smile at the crowds lining their motorcade route in Dallas, Texas, on Nov. 22, 1963. Minutes later the President was assassinated as his car passed through Dealey Plaza.(Bettmann/CORBIS) #

The Presidential motorcade on Main Street approaches Dealey Plaza, Dallas, on Nov. 22, 1963. (Cecil Stoughton/White House via EPA) #

American president John F. Kennedy is struck by an assassin's bullet as he travels through Dallas in a motorcade, November 22. 1963. Next to him is his wife Jacqueline and in the front seat is Texas governor John Connally. (Three Lions/Hulton Archive/Getty Images) #

The limousine carrying mortally wounded President John F. Kennedy races toward the hospital seconds after he was shot in Dallas. (Justin Newman/Associated Press) #

Spectators hit the ground in Dallas after President Kennedy was shot. (UPI) #

Women burst into tears outside Parkland Hospital upon hearing that President John F. Kennedy died from a shooting while riding in a motorcade in Dallas. (Associated Press) #

The view from the sixth floor window of the Texas School Book Depository in Dallas, from which Lee Harvey Oswald is thought to have assassinated President John F. Kennedy. This photograph was taken approximately one hour after the assassination. (Hulton Archive/Getty Images) #

Jacqueline Kennedy, with bloodstains on her clothes, holds hands with her brother-in-law, Attorney General Robert Kennedy, as the coffin carrying the body of President John F. Kennedy is placed in an ambulance after arriving at Andrews Air Force Base, Md. near Washington. (Associated Press) #

Lyndon B. Johnson is sworn in as president as Jacqueline Kennedy stands at his side in the cabin of the presidential plane on the ground at Love Field in Dallas. Judge Sarah T. Hughes, a Kennedy appointee to the Federal court, left, administers the oath. In background, from left are, Associate Press Secretary Malcolm Kilduff, holding microphone; Jack Valenti, administrative assistant to Johnson; Rep. Albert Thomas, D-Texas.; Lady Bird Johnson; and Rep. Jack Brooks, D-Texas. (Cecil Stoughton/White House/JFK Library via AP) #

President Lyndon B. Johnson and his wife Lady Bird, left, console widow Jacqueline Kennedy moments after he was administered the oath of office in the cabin of the presidential plane at Love Field in Dallas, Texas, on Nov. 22. (Cecil Stoughton/White House via Associated Press) #

A young girl cries outside a memorial service being held for President John F. Kennedy at Harvard University on Nov. 23. (Ollie Noonan Jr./The Boston Globe) #

A horse-drawn caisson bearing the body of President John F Kennedy heads from the White House, background, to the Capitol for him to lie in state on Nov. 24, 1963. (Associated Press) #

President John F. Kennedy's flag-draped coffin in the Capitol Rotunda, Washington, D.C., on Nov. 24, 1963. (Bob Gomel/Time Life Pictures/Getty Images) #

Jacqueline Kennedy kisses the casket of her husband, President John F. Kennedy, lying in state in the rotunda of the U.S. Capitol in Washington, accompanied by their daughter Caroline, kneeling alongside, on Nov. 24, 1963. (Associated Press) #

Lee Harvey Oswald, accused assassin of President John F. Kennedy, reacts as Dallas night club owner Jack Ruby shoots at him from point blank range in a corridor of Dallas police headquarters, on Nov. 24, 1963. Plainclothesman at left is Jim A. Leavelle. (Bob Jackson/Dallas Times-Herald/Associated Press) #

Police and reporters react after the shooting of Lee Harvey Oswald, President Kennedy's assassin, in Dallas, Tex., Nov. 24, 1963. The hat belonging to Oswald's shooter, Jack Ruby, is shown. (Associated Press) #

Lee Harvey Oswald, accused assassin of President John F. Kennedy, is placed on a stretcher after being shot in the stomach in Dallas on Nov. 24. Nightclub owner Jack Ruby shot and killed Oswald as the prisoner was being transferred through the underground garage of Dallas police headquarters. (David F. Smith/Associated Press) #

John F. Kennedy Jr. salutes his father's casket in Washington, on Nov. 25, 1963, three days after the president was assassinated in Dallas. Widow Jacqueline Kennedy, center, and daughter Caroline Kennedy are accompanied by the late president's brothers Sen. Edward Kennedy, left, and Attorney General Robert Kennedy. (Associated Press) #

Robert Kennedy and Edward Kennedy with their sister-in-law Jacqueline Kennedy during the funeral of President John F Kennedy on Nov. 25, 1963 in Washington D.C. (Keystone-France/Gamma-Keystone via Getty Images) #

A sailor weeps as the caisson bearing the body of President John F. Kennedy travels past him and other mourners in Arlington National Cemetery in Arlington, Va. on the way to the burial site on Nov. 25, 1963.( Associated Press ) #

Jacqueline Kennedy is flanked by her brothers-in-law in the procession carrying the coffin of slain President John F. Kennedy from the White House to St. Matthew's Roman Catholic Church in Washington, on Nov. 25, 1963. (Associated Press) #

President Charles de Gaulle of France, center, and other dignitaries, salute as servicemen hold an American flag above the casket of slain President John F. Kennedy in Arlington National Cemetery in Arlington, Va. on Nov. 25, 1963. (Associated Press) #

Jacqueline Kennedy, widow of assassinated President John F. Kennedy, holds the U.S. flag that covered the coffin of her husband at Arlington National Cemetery in Arlington, Va. after the president was buried on Nov. 25, 1963. (Eddie Adams/Associated Press) #

Marie Tippit, widow of police officer J.D. Tippit who was slain during the search for President John F. Kennedy's assassin, is led weeping from Beckley Hills Baptist Church in Dallas after funeral services for her husband on Nov. 25, 1963. The services began about the time those for Kennedy were ending in Washington. (Associated Press) #

A big question in Dallas is why Jack Ruby shot and killed Lee Harvey Oswald as the man accused of assassinating President Kennedy was being transferred from one jail to another, on Nov. 25, 1963. Ruby, whose real name is Rubenstein, is pictured as he was taken before a justice of the peace to be arraigned on murder charges. (Associated Press) #

A flag flies at half-staff above the White House in Washington, D.C. on Nov. 22. President Barack Obama ordered that flags be lowered at government buildings to mark the 50th anniversary of President John F. Kennedy's assassination. Obama says the anniversary is a day to honor Kennedy's memory and 'celebrate his enduring imprint on American history.' Obama says Kennedy's vision for the U.S. and the world lives 'in the generations he inspired." (Pablo Martinez Monsivais/Associated Press) #

People visit the gravesite of former U.S. President John F. Kennedy at Arlington National Cemetery on Nov. 22, in Arlington, Virginia. Remembrance ceremonies will be held across the United States on Nov. 22, the 50th anniversary of the assassination of President Kennedy. (Chip Somodevilla/Getty Images) #

Japanese visitors fold paper cranes to pay their respects to the late U.S. President John F. Kennedy at a memorial venue specially set for his Japanese fans in Tokyo, Japan on Nov. 22, to mark the 50th anniversary of his assassination. Japanese JFK fans took photos with his portrait, folded paper cranes and watched his inaugural ceremony on a monitor to express admiration on the anniversary. (Shuji Kajiyama/Associated Press) #

A man places a wreath outside the town hall of Berlin's district of Schoeneberg during the wreath laying ceremony for the 50th anniversary of the assasination of US President John F. Kennedy, in Berlin, Germany, on Nov. 22. (Ole Spata/EPA) #

A crowd gathers before a ceremony to mark the 50th anniversary of the assassination of John F. Kennedy, on Nov. 22, at Dealey Plaza in Dallas. President Kennedy's motorcade was passing through Dealey Plaza when shots rang out on Nov. 22, 1963 (Benny Snyder/Associated Press) #

An organizer removes orders of service from a bag displaying an image of former US President John F. Kennedy ahead of a memorial service in Runnymede, England on Nov. 22, to mark the 50th anniversary of his assassination. (Ben Stansall/AFP/Getty Images) #

People tour an exhibit at the Newseum dedicated to John F. Kennedy who was killed fifty years ago, on Nov. 22, in Washington, DC. (Mark Wilson/Getty Images) #