In 1974, two of the Alvin Fernald books (The Marvelous Inventions of Alvin Fernald and Alvin Fernald, Mayor for a Day) were combined into a single screenplay and presented in a two-part episode of The Wonderful World of Disney.  The screenplay was entitled The Whiz Kid and the Mystery at Riverton.  A few years ago it surfaced again on The Disney Channel.  As far as we know, this movie has never been released on videotape or DVD.  
 

Producer:  Ron Miller
Screenplay:  Herman Groves
Director:  Tom Leetch

Cast:

        Alvin Fernald - Eric Shea
        Shoie Shoemaker - Clay O'Brien
        The Pest - Kim Richards

        Mayor - Edward Andrews
        Treasurer - John Fiedler
        Fred Benson - Lonny Chapman