This collection consists of journals that cover the years between 1908 and 1920, documenting his experiences in Europe, Canada, and the United States. These handwritten journals, mainly in German, are illustrated with photographs and drawings done by Leonpacher. They also contain some correspondence and other added items. Furthermore, the collection consists of digitized copies of these journals, as well as a DVD of Louisiana Air Tours.

This collection was donated by Dr. Leonpacher’s widow Fanny (Mrs. John Doba), and son Robert J. Leonpacher. The diaries were digitized by Brian Butcher of Video 1 for Leslie Leonpacher, Louis’s granddaughter, who produced a documentary film on Dr. Leonpacher.