The intro to Don't Tread on Me uses the melody from West Side Story's “America.”
That melody was composed by Leonard Bernstein for the 1957 musical, with lyrics by Stephen Sondheim. Metallica incorporated the recognizable idea into the opening of Don't Tread on Me before moving into the song's compact heavy-metal arrangement.
The Metallica track takes its title from the motto on the Gadsden flag, whose snake also appears on the album cover. The song's patriotic imagery and its musical quotation connect its subject matter to a broader American cultural reference, although the band presents the idea through its own hard-rock style.
The song is sometimes overlooked because it was not one of the album's five commercial singles. It was sent to rock radio promotionally, but it did not receive a commercial single release. The West Side Story connection concerns the intro's melody, not the song's complete structure or lyrics.