President John F. Kennedy was riding in a motorcade through the streets of Dallas, Texas, when a gunman fired from a nearby building. Stunned onlookers ran for cover, and the president's driver sped toward a hospital. The young president could not survive his terrible wounds, meaning Vice President Lyndon B. Johnson would take his place. Police quickly tracked down Kennedy's killer, but the man's troubling background and puzzling behavior raised questions that seemed impossible to answer. Although Kennedy's life had been cut short, his presidency changed the country in ways still felt today.