The "cultural decade" of the 1960s is more loosely defined than the actual decade. It begins around 1963–1964 with the John F. Kennedy assassination, the Beatles' arrival in the United States and their meeting with Bob Dylan, and ends around 1969–1970 with the Altamont Free Concert, the Beatles' breakup and the Kent State shootings, or with the withdrawal of troops from Vietnam and the resignation of U.S. President Nixon in 1974.