Springsteen called Mr. Seeger "the father of American folk music." In a concert at Madison Square Garden celebrating Mr. Seeger's 90th birthday, Springsteen introduced him by saying, "He's gonna look a lot like your granddad that wears flannel shirts and funny hats. He's gonna look like your granddad if your granddad can kick your ass. At 90, he remains a stealth dagger through the heart of our country's illusions about itself."
Born May 3, 1919, to a musicologist father and concert violinist mother, Mr. Seeger first encountered folk music at 16, picked up the ukulele and banjo in the next few years, honored Harvard University by dropping out in 1938, and soon was hopping freights across the United States.
He was a compadre of Woody Guthrie and Lead Belly in the 1940s, and in the late 1940s to the late 1950s was part of the folk group the Weavers. He became a political hero for his refusal to cooperate with the House Un-American Activities Committee in the 1950s, and for his roles in the '60s civil-rights and antiwar movements. He has served as a banjo-playing grandfather figure to the folk community for as long as anyone can remember. In 2011, he led Occupy protests in Manhattan. His wife Toshi died in July, 11 days shy of their 70th wedding anniversary, yet Mr. Seeger played that September at Farm Aid.
In 1998, he told The Inquirer he didn't like thinking of himself as having a "career."
"That word implies seeking fame and fortune," said the cowriter of "If I Had a Hammer" and "Where Have All the Flowers Gone?" At the time, a tribute album titled Where Have All the Flowers Gone? had just come out on West Chester's Appleseed Recordings, his label for almost two decades. "I've just got jobs to do. My main purpose as a musician is to put songs on people's lips, not just in their ear."
On Tuesday, Jim Musselman, the head of Appleseed, said in a statement that Mr. Seeger "will live on in the hearts and minds of so many for years to come. His vision of peace and justice and equality for all will live on and continue to influence. Like a ripple that keeps going out from a pond, Mr. Seeger's music will keep going out all over the world spreading the message of nonviolence and peace and justice and equality for all. Wherever people are fighting to be free or fighting for equality, Pete's songs and Pete's vision will be there with them."
Gene Shay, longtime folk-music hero in the Philadelphia area and host of The Folk Show on WXPN-FM, said by phone that Mr. Seeger "has been so inspirational, so much of an idol, an icon. He spearheaded so many great things." Shay called him more than simply a musical figure: "Whenever I had a question about whether some action was ethical or appropriate, I would ask myself, 'What would Pete Seeger do?' He would never sell out, he would always take the high road. He was a man of great principles, great work ethic."
Shay said that when Mr. Seeger agreed to play at the first Philadelphia Folk Festival in 1961, "we were ecstatic, and we called everyone, we said, 'Pete's coming,' and that put us on the map. We sent him his check later, and he sent it back, with a message, 'Why don't you use this for your next festival?' "
Shay noted that "down just about until the end, Pete lived in this little place by the Hudson River and got up every day to chop wood for his potbellied stove." (Cahill-Jackson said Mr. Seeger had been chopping wood only a few days before going into the hospital.) He stayed fit, often doing push-ups before shows.
This champion for world music popularized Caribbean, Israeli, and African tunes. "He wanted the world to exchange musics," Shay said, "wanted people to understand we are all one. He got us and our children closer to that mind-set."
Mr. Seeger made music of unflagging optimism, often singing for children. Songs associated with him like "Old Dan Tucker" were the basis for Springsteen's 2006 album The Seeger Sessions.
"People often say to me, 'Don't you get discouraged? Are you some kind of Pollyanna?' " Mr. Seeger, who frequently broke into song during interviews, told The Inquirer. "I tell them that I say 'the hell with it' every night around 9:30, then I get up the next morning. Besides, if you sing for children, you can't really say there's no hope."
For Dan DeLuca's playlist of Pete Seeger songs, go to www.inquirer.com/seeger.
Staff writer John Timpane contributed to this article.