The Captain Hamilton Coolidge Collection contains materials related to the wartime experience of Hamilton Coolidge, a World War I pilot with the United States Army. Most of the collection contains official military documents related to Captain Coolidge and his time with the 94th Aero Squadron, such as his personnel record, memos, and orders from headquarters. Also included are photographs, a plane manual for a Morane-Saulnier Model A, and awards and certificates granted to Captain Coolidge.
Though the collection contains a published book of his correspondence (Letters of an American Airman: Being the War Records of Capt. Hamilton Coolidge, USA. 1917 – 1918), only two original letters are included: a telegram from the Coolidge family and a letter from Douglas Campbell. The location of the remainder of Coolidge's correspondence, if it still exists, is unknown.