Folk singer Mary Travers, a member of Peter, Paul and Mary, died Wednesday (Sept. 16) at a hospital in Danbury, Conn., following a lengthy illness. She was 72. The cause of death was complications from chemotherapy that followed a bone-marrow transplant she underwent several years ago for the treatment of leukemia. With Peter Yarrow and Paul Stookey, Travers helped define the folk music movement of the ’60s. Their self-titled debut album, featuring “Lemon Tree” and “If I Had a Hammer,” spent seven weeks at No. 1 and sold more than 2 million copies following its release in 1962. The trio’s recordings of “Blowin’ in the Wind” and “Don’t Think Twice, It’s All Right” helped Bob Dylan attract a mainstream audience. Their hits also include “Where Have All the Flowers Gone,” “Puff the Magic Dragon” and a cover of John Denver‘s “Leaving on a Jet Plane.” Peter, Paul and Mary were also on the front lines of the civil rights movement, performing at the March on Washington in 1963 and participating in the voting-rights marches in Alabama in 1965. After the trio broke up in 1970, Travers released a series of solo albums. She was born in Louisville, Ky., and grew up in the Greenwich Village area of New York City. Her survivors include her husband and two daughters.