Mr. Havens had been among the first to arrive at the performers' staging area in nearby Liberty. As the afternoon wore on and the crowd, estimated at 500,000 people, waited for the show to begin, concert organizers persuaded Mr. Havens, along with guitarist Paul Williams and drummer Daniel Ben Zebulon, to squeeze into a helicopter with their two conga drums and two guitars for the quick ride to the festival stage.
"I had the least instruments and the least guys," Mr. Havens explained in a 2008 interview with Bloomberg Television, "and they said, 'Richie, would you go over now?' I said, 'Yeah, it's about time, I've been here since 5 o'clock in the morning.' "
Mr. Havens and his band mates opened Woodstock shortly after 5 p.m. with "Minstrel From Gault." After their regular set, they did multiple encores to buy time for fellow performers still struggling to reach the site.
Richard Pierce Havens was born on Jan. 21, 1941, in the Bedford-Stuyvesant neighborhood of Brooklyn, New York, the eldest of nine children.
His father made tables and "was a pretty good musician too, a piano player with a feel for jazz," Mr. Havens wrote in a 1999 memoir. He said that his grandmother, Beatrice Elizabeth Gay, "broadened my musical appreciation at every opportunity, teaching me Jewish folk songs and Irish ballads and playing old recordings of Caribbean island music she had carried with her from Barbados."
He graduated from street-corner doo-wop groups to singing with the McCrea Gospel Singers as a teenager. Fired from his job as a portrait artist in Manhattan's Greenwich Village after missing work one day, he began performing music. His first album, Mixed Bag, was released in 1967.
He formed his own record label, Stormy Forest, which released six of his albums. They included Alarm Clock, which featured Mr. Havens' biggest hit single, his cover of George Harrison's "Here Comes the Sun."
Throughout the 1980s and '90s, Mr. Havens recorded television commercial jingles for companies including Amtrak, McDonald's Corp. and Cotton Incorporated, according to the Rolling Stone Encyclopedia of Rock & Roll.
Long active in environmental causes, Mr. Havens performed at the Environmental Inaugural Ball, an event associated with President Bill Clinton's inauguration in 1993. He played a sold-out concert in 2009 at the Bethel Woods Center for the Arts, on the site of Woodstock, to mark the festival's 40th anniversary.