Folk singer Pete Seeger, who established the music as an expression of community, conscience and social justice during a career that spanned eight decades, has died. He was 94.

Perhaps more than any performer, Seeger was instrumental in popularizing the traditional American folk repertoire. Many of the country’s most loved songs were passed along via Seeger’s voluminous recordings of them; his album discography runs to over 100 titles.

He viewed the sharing of folk songs as a democratic act. To participate in singing songs together – which Seeger encouraged in the group sing-alongs that were an inevitable feature of his concerts – was to participate in the inner workings of the country itself.

The banjo-plucking tenor’s name was synonymous with musical activism from the very beginning. Reared in the leftist folk movement of the 1940s, where he appeared alongside such iconic figures as Woody Guthrie, he established himself as a member of the Almanac Singers, a group with deep ties to the U.S. labor movement.

Seeger was briefly a major pop star in the early 1950s: His quartet the Weavers recorded a slickly produced version of Lead Belly’s “Goodnight Irene” that rivaled Patti Page’s “The Tennessee Waltz” as the biggest single of 1950.

But Seeger’s career ran aground during the anti-Communist ferment of the era. A former member of the American Communist Party, he refused to answer questions during an appearance before the House Un-American Activities Committee, resulting in a conviction for contempt of Congress that derailed him professionally and left him banned from network TV for more than a decade.

Nonetheless, he was an idol of the nascent folk revival of the ‘60s; his compositions “Where Have All the Flowers Gone,” “If I Had a Hammer” and “Turn, Turn, Turn” were respectively recorded by the Kingston Trio, Peter, Paul & Mary and the Byrds with great commercial success.

He was closely identified with the ‘60s civil rights movement, and had a hand in adapting the 1901 Baptist hymn “I’ll Overcome Someday” into the anthem “We Shall Overcome,” which he helped popularize on a like-titled 1963 live album. He was also vocal in his endorsement of nuclear disarmament, an end to the Vietnam War and environmental protection and his opposition to capital punishment.

An enduring icon of the folk community, his music and philosophy have been embraced by generations of artists, including such performers as Bob Dylan (whose original songs were first championed by Seeger) and Bruce Springsteen (who paid homage with “We Shall Overcome: The Seeger Sessions,” a 2006 recital of his material.

Springsteen later defined Seeger’s import for the New Yorker’s Alec Wilkinson: “He had a real sense of the musician as historical entity — of being a link in the thread of people who sing in others’ voices and carry the tradition forward…(and a sense) that songs were tools, and, without sounding too pretentious, righteous implements when connected to historical consciousness.”

Seeger was born May 3, 1919, in New York. His parents were Harvard-educated musicologist (and pacificist) Charles Seeger and concert violinist and educator Constance Edson Seeger. When he turned seven, his parents divorced, and his father soon married his student, composer Ruth Crawford Seeger.

His half-siblings from that second union included the future folk singers Mike Seeger, co-founder of the New Lost City Ramblers, and Peggy Seeger, who married British folk star Ewan MacColl.

Seeger took up the ukulele as a boarding school student. He began playing the banjo after hearing folklorist Bascom Lamar Lunsford at a 1936 folk festival in North Carolina. (He would later become adept at six- and 12-string guitar and recorder).

By the time he enrolled at Harvard, Seeger was reading leftist literature like the magazine New Masses and the muckraking journalists Lincoln Steffens and Mike Gold. He joined the Young Communist League in 1936. After dropping out of Harvard in 1938, he got his first semi-professional musical experience as a member of a touring puppet theater.

In 1940, he got a job in Washington, D.C. as an assistant to a family friend, folklorist Alan Lomax, head of the Library of Congress’ Archive of American Folk Song. That year, through Lomax, he met Oklahoma-born singer-songwriter Guthrie at a benefit concert for migrant workers. He was soon traveling with Guthrie, and performed with him on “Back Where I Come From,” the weekly CBS Radio folk show produced by Lomax.

In 1941, Seeger became a founding member of the Almanac Singers, a politically charged folk unit whose free-floating membership also included his New York roommates, writer-musician Millard Lampell and Arkansas-born singer Lee Hays, as well as Lomax’s sister Bess Lomax Hawes and Guthrie. The group recorded for Keynote Records, and was closely identified with pro-union activities and, initially, with anti-war sentiments. (The group changed its tune after Germany’s invasion of Russia.)

In 1942 – the same year he joined the American Communist Party – Seeger was drafted into the wartime Army; the following year, he married Japanese-American Toshi-Aline Ohta. The couple’s first child, also named Peter, died while Seeger was stationed overseas.

Following his return from the service, Seeger was instrumental in the founding of People’s Songs, a group devoted to the dissemination of pro-labor material and new compositions. Hays and singer Ronnie Gilbert were present at the group’s first meeting, and another singer-songwriter, Fred Hellerman, was soon contributing songs to its monthly bulletins (which served as a basis for such later folk magazines as Sing Out! and Broadside, in which Seeger was also active).

In 1948, Seeger published the first edition of his book “How to Play the 5-String Banjo,” still a basic text today.

The following year, he co-authored “If I Had a Hammer” with Hays for performance at a benefit for imprisoned Communist Party leaders. He and his family also narrowly escaped injury that September during a riotous protest of a concert appearance by African-American singer-actor-leftist Paul Robeson in Peekskill, N.Y.

The Weavers, co-founded by Seeger, Hays, Gilbert and Hellerman in 1948, were signed to Decca Records in 1949 by producer-arranger Gordon Jenkins, whose lushly orchestrated renderings of folk tunes led to the group’s massive success.

Their first hit, “Goodnight Irene,” held the No. 1 slot on the U.S. charts for 13 weeks, equalling the stay of “The Tennessee Waltz.” Other Weavers numbers reached the top five in 1950-52: the Israeli folk song “Tzena Tzena Tzena” (No. 2), Guthrie’s “So Long (It’s Been Good to Know Ya)” (No. 4) and the traditional “On Top of Old Smoky” (No. 2).

However, even though Seeger moved away from the Communist Party in the late ‘40s, the Weavers’ leftist affiliations led to scrutiny by the FBI, red-baiting publications like Red Channels and the tabloid press. A mountain of negative publicity forced the group to disband in 1952.

Seeger was subsequently subpoenaed by HUAC, and testified before the committee in New York in 1955. Declining to invoke the Fifth Amendment (as Hays did at his appearance), he said, “I am not going to answer any questions as to my association, my philosophical or religious beliefs or my political beliefs, or how I voted in any election, or any of these private affairs. I think these are very improper questions for any American to be asked.”

Cited for contempt, he was ultimately convicted and sentenced to prison in 1961, but an appellate court overturned the conviction in 1962.

Though the Weavers were effectively blacklisted, their manager Harold Leventhal undertook a gamble and resuscitated their reputation with a concert at New York’s Carnegie Hall on Christmas Eve 1955. A popular recording of the rousingly received event was issued by Vanguard Records in 1957.

Seeger continued to tour with the group before embarking on a solo career in 1958. He recorded prolifically for Moses Asch’s independent label Folkways.

Though his career remained under a cloud, Seeger was a greatly admired figure among the musicians and fans who stoked the so-called “folk revival” of the late ‘50s.

In 1959, he helped organize the first Newport Folk Festival with promoter George Wein. He was a central figure at the Rhode Island event in its early years, and he championed such young luminaries as Dylan (with whom he split after his electrified set in 1965) and Joan Baez. His popularity did not keep ABC from barring him from its early-‘60s folk series “Hootenanny,” an act that led folk stars like Baez to abandon the show.

Seeger’s visibility as an advocate for burgeoning civil rights activism in the U.S. culminated in a 1963 Carnegie Hall concert mainly comprising “movement songs.” Columbia Records released an album of the show, “We Shall Overcome,” which reached No. 42. In 1964, his Columbia single “Little Boxes,” a cover of a Malvina Reynolds song mocking conformity, hit No. 70.

While Seeger remained poison to network TV programmers, he secured airtime as the host of “Rainbow Quest,” a weekly series modestly produced by an independent New York UHF station. The show, which ran in 1965-66, featured him interviewing and performing with such revered performers as the Stanley Brothers, Mississippi John Hurt, Doc Watson, Rev. Gary Davis and Johnny Cash.

He finally returned to national TV in 1967, but not without controversy. He was scheduled to perform “Waist Deep in the Big Muddy,” an original song sharply critical of the Vietnam War, on CBS’s “Smothers Brothers Comedy Hour.” After the number was lopped from the show by network censors, its hosts protested and a furor ensued, and the song aired on a later telecast.

Always a man who loved the land – he built his family’s log cabin in upstate Beacon, N.Y., with his own hands – Seeger became increasingly active in the environmentalist movement in the mid- and late ‘60s.

He founded a group devoted to cleaning up the state’s severely polluted Hudson River in 1966, and three years later he launched the sloop Clearwater as a water-born performance space to publicize environmental rehabilitation. His 1973 album “Rainbow Race” featured several songs with environmental themes.

Seeger could still take sustained heat for his outspoken views, and for actions like a 1972 trip to North Vietnam as the conflict continued to rage. But as the years progressed, he moved comfortably into the role of elder folk statesman.

In 1975 he released “Together in Concert” with Woody Guthrie’s son Arlo, who would become a regular onstage partner. The year 1980 was highlighted by a pair of reunion concerts at Carnegie Hall with the Weavers. “The Weavers: Wasn’t That a Time,” a feature documentary about the shows and the group’s history, was released in 1982; it was directed by Jim Brown, who later helmed the 2008 PBS documentary about Seeger, “The Power of Song.”

Despite his controversy-courting history, Seeger was accorded many of the accolades accorded the musical elite as his performing career wound down.

He received three Grammy Awards (for best traditional folk album in 1997 and 2009 and for best children’s album in 2011) and a Grammy Lifetime Achievement Award in 1993, and was named a Kennedy Center Honoree in 1994.

Appleseed Records released an all-star two-CD Seeger tribute, “Where Have All the Flowers Gone,” in 1998.

He published an autobiography, “Where Have All the Flowers Gone,” in 1993, and was the author of several folk songbooks.

In 2009 – nearly 48 years after his conviction for contempt of Congress — he performed at President Barack Obama’s inaugural celebration.

True to form, he remained a man of the people and stayed on the firing line. In 2011, at the age of 92, he marched on a pair of canes in an Occupy Wall Streeet demonstration in Manhattan, joined by his grandson and Arlo Guthrie.

One of his last recordings was a version of Dylan’s “Forever Young” for “Chimes of Freedom,” a two-CD collection benefiting Amnesty International. He was nominated for a 2014 Grammy for his spoken word release “The Storm King.”

President Barack Obama released a statement following Seeger’s passing that read, “Once called ‘America’s tuning fork,’ Pete Seeger believed deeply in the power of song. But more importantly, he believed in the power of community – to stand up for what’s right, speak out against what’s wrong, and move this country closer to the America he knew we could be. Over the years, Pete used his voice – and his hammer – to strike blows for worker’s rights and civil rights; world peace and environmental conservation. And he always invited us to sing along. For reminding us where we come from and showing us where we need to go, we will always be grateful to Pete Seeger. Michelle and I send our thoughts and prayers to Pete’s family and all those who loved him.”

Seeger’s wife Toshi died in July 2013. He is survived by son Daniel and daughters Mika and Tinya.