Legendary American folk singer and political activist Pete Seeger has died at the age of 94.

His family said Seeger passed away Monday of natural causes at New York-Presbyterian Hospital.

Seeger was the son of a musicologist who introduced him to rural American folk music while he was a student at a Connecticut boarding school. He later met and befriended two other legendary American folk singers: the black blues musician Lead Belly, and Woody Guthrie, with whom he toured across the country performing at benefits for labor activists during the Great Depression of the 1930s.

After serving in World War II, he founded the Weavers, a quartet that achieved wide popularity in the early 1950s with such songs as Kisses Sweeter Than Wine, If I Had a Hammer, and Goodnight, Irene, sparking a revival in American folk music.

However, the group’s success ended after Seeger was cited for his earlier ties to the Communist Party. He was barred from performing on television and eventually called before the House Un-American Activities Committee, where he refused to answer questions about his political activities. He was tried and convicted for contempt of Congress and sentenced to jail, but the sentenced was eventually overturned.

Seeger continued to draw huge audiences at college campuses and small nightclubs, and he took part in such causes as civil rights and environmentalism. His arrangement of We Shall Overcome, which had its roots as a gospel song, became the anthem of the civil rights movement of the 1960s.

Seeger also wrote such popular songs as Turn, Turn, Turn and Where Have All the Flowers Gone? He earned numerous awards and accolades late in his career, including a Grammy Award in 1993 for lifetime achievement. He was also named a Kennedy Center honoree in 1994, and inducted into the Rock and Roll Hall of Fame in 1996 as an early influence.

In 2009, he performed at a concert staged at the Lincoln Memorial in celebration of President Barack Obama’s first inauguration.