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.

Travers brought a powerful voice and an unfeigned urgency to music that resonated with mainstream listeners. 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.

Travers was outspoken in her support for the civil-rights and anti-war movements. Peter, Paul and Mary went on to perform at the 1963 March on Washington and joined the voting-rights marches from Selma to Montgomery, Alabama, in 1965.