I believe that it is symbolic for the disappearance of "good time rock-n-roll," and the emergence of new styles. He was saying goodbye to the morally sound life as it was (musically, politically, and the way people thought in general). The Miss America Pageant and apple pie were (and sometimes still are) associated with classic American life/lifestyle; hence, "Bye bye Miss American Pie.".
Symbolism, metaphors, and repetition are represented throughout the entire refrain. In the lyrics, "Drove my Chevy to the levee, but the levee was dry," the dry levee is a metaphor for rock music being (figuratively) sucked dry. The Chevy is yet another American icon that can be symbolic for the American spirit. The last line of the chorus is repeated twice and is a direct reference to a Buddy Holly song called "That"ll be the Day that I Die." The use of repetition is a literary technique that McLean uses to emphasize the line continually reminding the listener of his purpose. As well as being a twist on the Buddy Holly jingle, the line can also be construed as the abandoning of the rock scene by era songwriters. The double meaning in this line adds to the charm and cleverness of the melody. .
Though puns, metonymy, irony, and imagery are represented all through the tune, the first and second stanzas embody one central theme. The first verse lays the foundation for the premise of the song. In a bit of a flashback, McLean tells of the principle event that shaped the outcome of his life. The last line of that canto, which happens to be the last line of them all, epitomizes the fundamental idea of the melody. It can also be looked at as a loose example of hyperbole. Though music did not literally "die," it did change. Using such a strong word increases the effect of the line. "The day the music died" signifies the loss of the three musicians, as well as a loss of innocence. Feb. 3, 1959 marked the beginning of the slow death of rock that the song further chronicles.