The introduction to Metallica's “Don't Tread on Me” interpolates the melody “America.”
“America” was composed by Leonard Bernstein for the musical West Side Story. Metallica uses the recognizable melodic idea at the beginning of the Black Album track before moving into the song's heavy-metal arrangement.
The reference is brief and instrumental, so listeners may notice the tune without immediately identifying its source. It is an interpolation rather than a full cover of the musical number, meaning the album incorporates a melodic passage inside a newly written song.
The connection is sometimes confused with patriotic American songs such as “The Star-Spangled Banner” or “God Bless America.” The relevant source is Bernstein's “America,” a song from West Side Story, not a national anthem or traditional patriotic standard.