The Solomon Mullin World War II Collection consists of materials from Solomon 's service as a Boeing B-17 Flying Fortress navigator and instructor in the 385th Bomb Group for the United States Army Air Forces during World War II. The documents, which date from 1942 to 1999, include textual and visual materials.

A large component of the textual documents is related to Mullin’s training as a navigator and bombardier for the USAAF from 1942 to 1943. The materials are comprised of printed study guides, exams, charts, flight logs, diagrams with Mullin’s annotations, as well as handwritten notes covering gunnery, ballistics, and aircraft machine gun designs. There is also a course packet on close cooperation between the Army Air Forces and Ground Forces with Solomon's handwritten notes, course outline, and maps.

Additionally, there are other textual documents that date from 1944 to 1999, which include a graduation announcement from the Army Air Forces Navigational School, San Marcos, Texas, for the class of 1944, as well as both Mullin’s and his wife’s war ration books. There is a brochure regarding the 385th Bomb Group, certificates, military orders, and official correspondence regarding Mullin’s Air Medal with Oak Leaf Cluster, and Distinguished Flying Cross awards. Lastly, there is correspondence between Mullin and the Library of Congress, Geography and Map Division associated with his donation of “flak maps” in 1999.

Included with the collection is a scrapbook created by Mullin that charts his experience starting in 1942, with his training at the Army Air Forces Technical School in Sioux Falls, South Dakota and the Harlingen Army Gunnery School in Harlingen, Texas. The materials then follow Mullin’s service until the end of the war in 1945. The scrapbook contains clippings, printed ephemera, travel approval forms, certificates, his diploma from Harlingen Army Gunnery School, official correspondence regarding his awards, and 122 mostly 4x5” black-and-white photographic prints. The prints depict Mullin and other service men, such as Joe McKee, preparing to leave by train for Sioux Falls. There are pictures of the men posing in uniform with their companions, interior views of the barracks, as well as candid images of other service men. There are also formal military photographs of Mullin. Some of the photographs include captions.

In addition to the photographic prints from the scrapbook, the visual materials also include 363 predominantly 3x4” and 4x5” black-and-white photographs, 4 3x5” Kodachrome prints, and 80 negatives. These images, taken by Mullin, illustrate his service during World War II, as well as personal elements of his life. The photographs feature candid scenes of service men at leisure in the barracks, and many informal individual and group portraits. There are images of B-17 aircraft in formation while in flight, aerial views of targets, and pilots seated within the aircraft. The other piece of the collection is related to Mullin’s civilian home life. There are photographs of Mullin’s family, their farm, friends, scenic views, parties, baseball games, as well as a series of photographs and negatives that appear to be taken through the viewfinder of a microscope. In addition, there are postcards from his travels.

Lastly, part of the collection consists of Mullin’s military flight plans, charts, and ordnance maps from when he was serving in Europe, from 1943-1945. The maps are annotated by Mullin, charting his missions and courses to destinations.