A file photo shows from left, Pete Seeger, his grandson Tao Rodriguez-Seeger, Bruce Springsteen, will.i.am, and Samuel L Jackson perform at the We Are One: ...
Musician Pete Seeger sings Amazing Grace during a concert celebrating his 90th birthday in New York in May 2009.
President Clinton presenting folk musician Pete Seeger with a 1994 National Medal of Arts at the White House.
This 1994 file photo shows actor Kirk Douglas, standing from left, singer Aretha Franklin, singer Peter Seeger and seated from left, director Harold Prince and ...
This file photo from 2011 shows Pete Seeger, 92, marching with nearly a thousand demonstrators sympathetic to the Occupy Wall Street protests for a brief ...
This file photo shows Pete Seeger, left, age 74, who hadn't sung with Burl Ives, right, age 84, for at least 40 years, singing together ...
This file photo shows folk singer Pete Seeger, left, performing at the Rally for Détente at Carnegie Hall in New York.
Pete Seeger, who helped create the modern American folk music movement and co-wrote some of its most enduring songs such as If I Had a Hammer and adapted We Shall Overcome died on Monday at the age of 94.
Here are 10 things you must know about this champion of folk music.
1. Dropping out of Harvard in 1938 after two years as a disillusioned sociology major, he hit the road, picking up folk tunes as he hitchhiked or hopped freights. "The sociology professor said, 'Don't think that you can change the world. The only thing you can do is study it,'" Seeger said in October 2011.
2. He learned the five-string banjo, an instrument he rescued from obscurity and played the rest of his life in a long-necked version of his own design. On the skin of Seeger's banjo was the phrase, "This machine surrounds hate and forces it to surrender" - a nod to his old pal Guthrie, who emblazoned his guitar with "This machine kills fascists".
3. Seeger was credited with popularising We Shall Overcome, which he printed in his publication People's Song, in 1948. He later said his only contribution to the anthem of the civil rights movement was changing the second word from "will" to "shall," which he said "opens up the mouth better".
4. An influential pamphlet listing performers with suspected Communist ties called Red Channels, appeared in June 1950 and listed Seeger's name. This was long after he had left the party but he continued to describe himself as a "communist with a small 'c' "
5. Subpoenaed by the House Un-American Activities Committee in 1951, he said he had done nothing conspiratorial in his entire life. Seeger offered to sing the songs mentioned by the congressmen who questioned him. The committee declined.
6. Seeger was signed to a major label, Columbia Records, in 1961, but he remained unwelcome on network television. An ABC show which capitalised on the folk revival, refused to book Seeger, causing other performers (including Bob Dylan, Joan Baez and Peter, Paul and Mary) to boycott it. The show eventually offered to present Seeger if he would sign a loyalty oath. He refused.
7. Seeger's sometimes ambivalent relationship with rock was most famously on display when Dylan "went electric" at the 1965 Newport Folk Festival. Witnesses say Seeger became furious backstage as the amped-up band played, though just how furious is debated. Seeger dismissed the legendary tale that he looked for an axe to cut Dylan's sound cable, and said his objection was not to the type of music but only that the guitar mix was so loud you couldn't hear Dylan's words.
8. The Hudson River was a particular concern of Seeger. He took the sloop Clearwater, built by volunteers in 1969, up and down the Hudson, singing to raise money to clean the water and fight polluters.
9. He also offered his voice in opposition to racism and the death penalty. He got himself jailed for five days for blocking traffic in Albany in 1988 in support of Tawana Brawley, a black teenager whose claim of having been raped by white men was later discredited. He continued to take part in peace protests during the war in Iraq, and he continued to lend his name to causes. "There's not dozens of people now doing what I try to do, not hundreds, but literally thousands. ... The idea of using music to try to get the world together is now all over the place."
10. Seeger's 90th birthday was celebrated in May 2009 with a concert in New York's Madison Square Garden that drew 15,000 spectators and performers, including Bruce Springsteen, John Mellencamp, Emmylou Harris, Arlo Guthrie, Joan Baez and Kris Kristofferson. Proceeds went an environmental group Seeger founded.