“Don’t Tread on Me” is the Metallica song whose intro interpolates Leonard Bernstein’s “America.”
The melody comes from “America,” a song Bernstein composed for the musical West Side Story. Metallica used that recognizable musical idea at the beginning of “Don’t Tread on Me,” creating a brief connection between a classic Broadway composition and a heavy-metal album.
An interpolation is not necessarily the same as a straightforward sample. It refers to the reuse or recreation of a musical passage within a new composition. The album’s notes identify the “Don’t Tread on Me” intro as interpolating Bernstein’s melody.
The song was included on the original 1991 album but was not one of its five commercial singles. It was issued to rock radio shortly after release, which can lead listeners to count it among the album’s official singles. The five commercial singles were “Enter Sandman,” “The Unforgiven,” “Nothing Else Matters,” “Wherever I May Roam,” and “Sad but True.”