The three-day gathering (actually held in nearby Bethel, N.Y.) is still a Rorschach test for how people view an era marked by massive challenges to social assumptions and political authority. Woodstock has come to be seen as either a symbol of what ails America today – drugs, immorality, relativism, and a general decline of civilization – or a joyous, peaceful celebration of human potential, exploration, and fresh possibilities,
Little about the concert was overtly political. "[T]hey are the most courteous, considerate, and well-behaved group of kids I have ever been in contact with...," a local police chief told a New York Times reporter at the time.
Perhaps it was a relief, a timeout, a moment to unwind when the Vietnam War and racial tensions dominated the headlines. Perhaps, in coming a month after the first moon landing, it was time to show humanity could be as one.
"The important thing that you've proven to the world," Max Yagur told the crowd, "is that a half million young people can get together to have fun and music ... and have nothing but fun and music, and I God bless you [sic] for it!"
Nearly a half million mostly young people managed to reach Mr. Yagur's farm, the site of the gathering, with around 2 million more stuck on jammed roads trying to get there.
Some see the massive turnout as a spontaneous burst of idealism that is echoed over the years in other public feel-good events, such as the throngs gathered on the Washington Mall for President Obama's "Yes, We Can" inauguration last January.
Unintentionally, Woodstock may have demonstrated a pre-Internet version of the power of "free" as an economic concept. Most of the crowd crashed the gates and paid nothing to attend. The organizers were left millions in debt. Yet by later selling movie and other rights they eventually made money.
Why should anyone take notice of an event that's faded as far into the past as the 1929 stock market crash had to those beaded, bearded, tie-dyed youths of 1969?
Some hint of Woodstock's meaning comes from a poll of Americans 16 years and older by the Pew Research Center. It found that while a "generation gap" in attitudes between young and old still exists, it's much less confrontational than four decades ago. The generations have learned to "disagree without being disagreeable," the report says.
Only about one-quarter of respondents thought there are still "strong conflicts" between generations today. And just 10 percent of those who were parents said they had had a serious conflict with their teenaged or young adult child. Nearly twice as many of these parents said that when they were teens themselves they had major disagreements with their own parents.
Maybe it is the legacy of the music that has brought them together.
Rock music no longer represents a "defiant counterculture" as it did then, the study says. In 1969, nearly half of adults surveyed said they actively disliked rock music. Now it is the most popular genre of music among all adult age groups under 65. The Beatles are the favorite musical act overall. Even among today's 16-to-29-year-olds, the lads from Liverpool ranked second only to Michael Jackson – and far ahead of current stars Kanye West and Carrie Underwood.
Last spring, the '60s musical "Hair" returned to Broadway. Nationwide, retro '60s fashions are gaining new fans. "Mad Men," the Emmy Award-winning drama, returns to TV this Sunday, depicting the buttoned-down, dark-suited days of the early '60s that were about to burst into the technicolor world of Woodstock.
Let's hope that tumultuous decade continues to fascinate, like a desire for perpetual youth and a search for deep meaning in life.