Mary Travers, whose ringing, earnest vocals with the folk trio Peter, Paul and Mary made songs like "Blowin' in the Wind," "If I Had a Hammer" and "Where Have All the Flowers Gone?" enduring anthems of the 1960s protest movement, died on Wednesday at Danbury Hospital in Connecticut. She was 72 and lived in Redding, Conn.
The cause was complications from chemotherapy associated with a bone-marrow transplant she had several years ago after developing leukemia, said Heather Lylis, a spokeswoman.
Ms. Travers brought a powerful voice and an unfeigned urgency to music that resonated with mainstream listeners. With her straight blond hair and willowy figure and two bearded guitar players by her side, she looked exactly like what she was, a Greenwich Villager directly from the clubs and the coffeehouses that nourished the folk-music revival.
"She was obviously the sex appeal of that group, and that group was the sex appeal of the movement," said Elijah Wald, a folk-blues musician and a historian of popular music.
Ms. Travers's voice blended seamlessly with those of her colleagues, Peter Yarrow and Paul Stookey, to create a rich three-part harmony that propelled the group to the top of the pop charts. Their first album, "Peter, Paul and Mary," which featured the hit singles "Lemon Tree" and "If I Had a Hammer," reached No. 1 shortly after its release in March 1962 and stayed there for seven weeks, eventually selling more than two million copies.
The group's interpretations of Bob Dylan's "Blowin' in the Wind" and "Don't Think Twice, It's All Right" translated his raw vocal style into a smooth, more commercially acceptable sound. The singers also scored big hits with pleasing songs like the whimsical "Puff the Magic Dragon" and John Denver's plaintive "Leaving on a Jet Plane."
Their sound may have been commercial and safe, but early on their politics were somewhat risky for a group courting a mass audience. Like Mr. Yarrow and Mr. Stookey, Ms. Travers was outspoken in her support for the civil-rights and antiwar movements, in sharp contrast to clean-cut folk groups like the Kingston Trio, which avoided making political statements.
Peter, Paul and Mary went on to perform at the 1963 March on Washington and joined the voting-rights marches from Selma to Montgomery, Ala., in 1965.
Over the years they performed frequently at political rallies and demonstrations in the United States and abroad. After the group disbanded, in 1970, Ms. Travers continued to perform at political events around the world as she pursued a solo career.
"They made folk music not just palatable but accessible to a mass audience," David Hajdu, the author of "Positively Fourth Street," a book about Mr. Dylan, Joan Baez and their circle, said in an interview. Ms. Travers, he added, was crucial to the group's image, which had a lot to do with its appeal. "She had a kind of sexual confidence combined with intelligence, edginess and social consciousness - a potent combination," he said. "If you look at clips of their performances, the camera fixates on her. The act was all about Mary."
Mr. Yarrow, in a statement on Wednesday, described Ms. Travers's singing style as an expression of her character: "honest and completely authentic."
Mr. Stookey, in an accompanying statement, wrote that "her charisma was a barely contained nervous energy - occasionally (and then only privately) revealed as stage fright."
Mary Allin Travers was born on Nov. 9, 1936, in Louisville, Ky. When she was 2 her parents, both writers, moved to New York. Almost unique among the folk musicians who emerged from the Greenwich Village scene in the early 1960s, Ms. Travers actually came from the neighborhood. She attended progressive private schools there, studied singing with the music teacher Charity Bailey while still in kindergarten and became part of the folk-music revival as it took shape around her.
"I was raised on Josh White, the Weavers and Pete Seeger," Ms. Travers told The New York Times in 1994. "The music was everywhere. You'd go to a party at somebody's apartment and there would be 50 people there, singing well into the night."
While at Elisabeth Irwin High School, she joined the Song Swappers, which sang backup for Mr. Seeger when the Folkways label reissued a collection of union songs under the title "Talking Union" in 1955. The Song Swappers made three more albums for Folkways that year, all featuring Mr. Seeger to some degree.
Ms. Travers had no plans to sing professionally. Folk singing, she later said, had been a hobby. At New York clubs friends like Fred Hellerman of the Weavers and Theodore Bikel would coax her onstage to sing, but her extreme shyness made performing difficult. In 1958 she appeared in the chorus and sang one solo number in Mort Sahl's short-lived Broadway show "The Next President," but as the '60s dawned she found herself at loose ends.
Ms. Travers's ringing vocals helped make the folk trio's songs enduring anthems of the 1960s protest movement.