The intro to “Don't Tread on Me” on Metallica's 1991 album interpolates music from “America.”
“America” was composed by Leonard Bernstein for the musical West Side Story. Metallica used part of that melody in the introduction to the sixth track on the album, creating a brief connection between a heavy-metal record and a celebrated Broadway score.
The connection is easy to miss because the interpolation appears in the introduction rather than as the song's main riff. “Don't Tread on Me” then moves into its own guitar-driven arrangement and lyrics, inspired by the imagery of the Gadsden flag.
The song title and album artwork reinforce one another: the cover contains a coiled snake derived from the Gadsden flag, whose motto is “Don't Tread on Me.” The musical reference is separate from that visual symbolism but appears in the same track.