According to Today in Labor History (with a HT to Tom Morello) today 70 years ago, Woody Guthrie wrote 'This Land Is Your Land'. You can see the original handwritten manuscript at woodyguthrie.org
Today in Labor History says: "Guthrie wrote “This Land Is Your Land” following a frigid trip – partially by hitchhiking, partially by rail – from California to Manhattan. The Great Depression was still raging. Guthrie had heard Kate Smith’s recording of “God Bless America” and resolved to himself: “We can’t just bless America, we’ve got to change it."
Here, Pete Seeger and Friends perform the song at Pete's 90th Birthday Concert.
You can see Bruce Springsteen play the song here, while Bruce and Pete Seeger play it here for President Obama's inauguration.
Here's one of my favorite versions, by Steve Earle: