The musical that introduced rock ’n’ roll to the theatrical stage, “Hair,” opened off Broadway on Oct. 17, 1967.

After a two- month run there, the show moved to a nightclub for another two months while the production’s creators concen- trated on refining their story and music before it opened at Broadway’s Biltmore Theater on April 29, 1968.

The show was created by two self-described “hippies,” Gerome Ragni and James Rado, who provided the story and the lyrics, and an established Canadian composer, Galt MacDermot, who had won a Grammy Award in 1961 for “African Waltz.”

“I had short hair, a wife and, at that point, four children. And I lived on Staten Island,” MacDer- mot would say later.

Ragni and Rado performed in the original off-Broadway and Broadway productions of “Hair,” along with a number of actors and musicians who would go on to greater fame: Diane Keaton, Ben Vereen, Keith Carradine, Barry McGuire, Ted Lange and Meat Loaf.

The musical focused on count- er-culture themes of the late 1960s, including the sexual revolution, drug use, nudity, anti-war protests and, especially, long hair on men, which had become increasingly popular in the 1960s.

“Gimme a head with hair,” the cast sings at one point. “Long beautiful hair, Shining, gleaming, streaming, flaxen, waxen ... Give me down to there, hair, shoulder length or longer ... Flow it, show it, long as God can grow it, my hair!”

It made for a very popular show.

“Hair” would run for 1,750 performances on Broadway and, soon after, productions would crank up across the U.S. and in London.

Arguably, “Hair” is best known for its striking music. You know the songs: “Let the Sunshine In” and “The Age of Aquarius” — which would be combined into a hit single for the Fifth Dimension — and “Easy to Be Hard,” which would be recorded with great success by Three Dog Night.

The original cast recording of “Hair,” released on May 6, 1968, would spend 13 weeks atop the Billboard 200 album chart in 1969, a year when an awful lot of memora- ble music was released (enjoy the list at right). No original Broadway cast album has since occupied Billboard’s top Album spot.

The album would sell 3 million copies and win a Grammy Award for Best Score from an Original Cast Show Album. In 2018, “Hair” would be named to the National Record- ing Registry list of significant cultural sound recordings.

“Hair” was extensively rewritten for its movie adaptation in 1979. A 2009 Broadway revival would win a Tony Award for Best Revival of a Musical.