The complete film of "Wheels Of Progress" can be found at: http://www.archive.org/details/Wheelsof1927
The entire film can be downloaded at: http://www.archive.org/details/AnAnswerA
Excerpt From "The Plow That Broke The Plains": http://www.archive.org/details/PlowThatBrokethePlains1
Prelinger Archives: http://www.archive.org/details/prelinger