This collection contains personal and business correspondence and photographs of Clinton A. Decker. The majority of personal correspondence is to Decker's future wife, Gertrude V. O'Brien. The letters, arranged chronologically, describe Decker's activities as a member of the American Advisory Commission of Railway Experts to Russia and reveal Decker's perspective on revolutionary Russia from 1917 to 1919. Included are detailed descriptions of Vladivostok, Harbin, and an account of the July Riots (July Days) in Petrograd, as well as a description of the Cossacks (and one of their leaders, Grigori Semenov) and their role in the revolution. A small amount of newspaper clippings and materials related to events around Decker's experiences is also found. Most of this correspondence has been published in Mission to Russia: An American Journal (Edited by Charles J. Decker, self-published, New York: 1994).

The business correspondence focuses on John F. Stevens's work as President of the Inter-Allied Technical Board for which Decker served as secretary. This correspondence is divided into three sections. The first contains Stevens's personal business files from July 26, 1919 to November 21, 1922, arranged chronologically by outgoing correspondence. The materials range from invitations to social events from Russian, Chinese and Japanese officials to letters from American and Canadian firms asking about possible business opportunities. Also included is a letter from an ex-member of the Chinese Eastern Railway Council who was arrested in Petrograd in 1918. He, and the other members of the Council, sought compensation after their release.

The second section contains correspondence Stevens received from the American Representative to the Technical Board, C.H. Smith, from April 30, 1919 to June 8, 1921, arranged chronologically by incoming letter. Much of the correspondence discusses Japanese presence in the region and the Allies' role in the internal conflicts of Russia. Also included are several detailed accounts of disturbances along the rail line such as impounding equipment and the harassment and murder of passengers. Copies of most of the memoranda are included; however enclosures (letters/invoices/telegrams) are not included in the files.