I saw on the Iplayer that there was a documentary about the song: Alice's Restaurant's by Arlo Gutherie. When I was living in Lexington Kentucky I did go and see Arlo play a set at a Movie Theatre. I enjoyed the gig. He was very funny. I could only remember the chorus of the song, that you "you can get anything you want at Alice's restaurant."
From the documentary I found that out that it is a tradition to hear the song at Thanksgiving. I didn't realize the song was political.