The Plow That Broke the Plains is a 1936 short documentary film which shows what happened to the Great Plains region of the United States and Canada when uncontrolled agricultural farming led to the Dust Bowl. It was written and directed by Pare Lorentz. The film was narrated by the American actor and baritone Thomas Hardie Chalmers.
In 1999, The Plow That Broke the Plains was selected for preservation in the United States National Film Registry by the Library of Congress as being "culturally, historically, or aesthetically significant".
The film was sponsored by the United States government (Resettlement Administration) to raise awareness about the New Deal and was intended to cost $6,000 or less; it eventually cost over $19,000 and Lorentz, turning in many receipts written on various scraps of paper, had many of his reimbursements denied and paid for much of the film himself. Lorentz later faced criticism for appearing to blame westward bound settlers for the ecological crisis by having eroded the soil of the Plains with unrestrained farming, but the film nonetheless succeeded in driving home the message of the severity of the problem caused by the misuse of land.
Lorentz worked on the film with composer Virgil Thomson, who shared Lorentz's enthusiasm for folk music and incorporated many folk melodies, along with other popular and religious music, into the soundtrack.
Virgil Thomson compiled a concert suite from his original score, which has been performed and recorded. Its first recording was made on RCA 78s in 1946 by the newly formed Hollywood Bowl Symphony Orchestra under its founder and first conductor, Leopold Stokowski. One of the earliest stereo recordings was made for Vanguard Records in 1961, again with Leopold Stokowski, this time conducting the Symphony of the Air. The original Vanguard LP and its later CD reissue also included a suite from Thomson's score for another Lorentz documentary, The River.
The film exists in at least three versions. The original includes an epilogue detailing the activities of the Resettlement Administration. The most common version today on DVD omits this final chapter. Finally, another contemporary version places the scrolling Prologue text before the opening credits.