The story is set in theUpper West Sideneighborhood in New York City in the mid-1950s, an ethnic,blue-collarneighborhood. (In the early 1960s much of the neighborhood would be cleared in anurban renewalproject for theLincoln Center, changing the neighborhood's character.)The musical explores the rivalry between the Jets and the Sharks, two teenage streetgangsof differentethnicbackgrounds. The members of the Sharks,from Puerto Rico, are taunted by the Jets, acaucasiangang.The young protagonist, Tony, a former member of the Jets and best friend of the gang leader, Riff, falls in love with Maria, the sister of Bernardo, the leader of the Sharks. The dark theme, sophisticated music, extended dance scenes, and focus on social problems marked a turning point in American musical theatre. Bernstein's score for the musical includes "Something's Coming", "Maria", "America", "Somewhere", "Tonight", "Jet Song", "I Feel Pretty", "A Boy Like That", "One Hand, One Heart", "Gee, Officer Krupke", and "Cool".