The John Upton Clowdsley Collection spans the years 1914-1962, and consists of drawings, photographs, and project cost estimate files. The records are primarily for residences in Stockton and San Joaquin County but his student work and drawings for the Stockton City Hall are also part of the collection. As a representation of architecture in the Central Valley, the collection enhances the strong northern California presence at the Environmental Design Archives. Furthermore, Clowdsley's residential work from the 1920-1950s provides insight into the contemporary style of and taste in residential architecture.

The collection is organized into three series: Personal Records, Office Records, and Project Records. The project records are the largest and the most valuable series in the collection as they represent more than 65 of Clowdsley's projects by drawings and photographs. The personal papers are limited and consist of Clowdsley's student work from the University of California, Berkeley. The office records are also limited. They include cost estimates index cards for approximately 160 of Clowdsley's projects.