It was crowded, wet, muddy and historic. This week brings the 40th anniversary of the Woodstock Music and Arts Fair on a 600-acre dairy farm north of New York City -- an icon of how young Americans influenced the national culture during the late 1960s. The event from Aug. 15-18, 1969, billed as "3 Days of Peace and Music," drew the largest concert audience ever -- perhaps 500,000 people, though crowd estimates vary.

It also became a benchmark of the "Age of Aquarius," as that period came to be called. (Woodstock festival posters describe "An Aquarian Exposition.") Images spread around the world of dancing hippies, peace symbols and legendary performers such as Jimi Henrix, Janis Joplin, Santana, the Grateful Dead, the Who, Joe Cocker, Joan Baez, Crosby, Stills, Nash & Young, Joni Mitchell, Creedence Clearwater Revival and the Jefferson Airplane. There were two soundtrack albums, a hit documentary film and a classic song by Mitchell that's sure to be on radio and TV this week.
Most importantly, the event symbolized a political turning point. It vividly demonstrated many young Americans' feelings about the Vietnam War, civil rights, the natural environment and new lifestyles. Concertgoers represented a "counter-culture" movement expressed with tie-dye fashions, long hair and illicit drugs. "Woodstock Nation," some called it.

Ripples from that "flower power" era changed our country. So in a way, you're affected by Woodstock even though you weren't there.
Now the festival is commemorated with several new books, an exhibit through November at the Rock and Roll Hall of Fame in Cleveland, a feature film (Taking Woodstock) reaching theaters Aug,. 28 and a director's cut two-DVD reissue of a 1970 Oscar-winning documentary featuring performances and interviews. In the video clip below, festival co-creator Michael Lang recalls making the movie.

Joni Mitchell wrote: "By the time we got to Woodstock / We were half a million strong / And everywhere was a song and a celebration." -- Lyrics from Woodstock, 1969 hit song

Historian says: "It was probably the end of the flower power movement. It was the last moment that young people felt they truly could change the world." -- Randy Roberts, history professor at Purdue University in West Lafayette, Ind..

Author says: "Woodstock was about backpacks and beards and bandanas and bonfires and tents and tepees. This was a pilgrimage." -- Rob Kirkpatrick, writer of 1969: The Year Everything Changed (2009)