The Hughes Tool Company series (1912-1990) encompasses the administrative, financial, and legal management of Hughes Tool Company. Materials within the series depict Howard Hughes' control of the company; his film, aeronautics, electronics, and real estate ventures; and his lawsuits and United States Senate hearing. The series also includes research reports on the corporate history of Hughes Tool Company and its subsidiaries, copyright histories for films Hughes produced, and correspondence from Hughes' associates searching for reels of Hughes' films domestically and internationally.

Materials contain photographs of the Hughes H-1 Racer aircraft from 1935 to 1945. The photographs primarily depict Howard Hughes standing with the plane or in the plane's cockpit. The plane was designed by Glenn Odekirk and built by Hughes Aircraft Company in 1935, the first plane produced by the company. Hughes broke several records in the H-1, including the landplane speed record in 1935. In 1937, Hughes broke his own transcontinental speed record by flying from Los Angeles, California to New York City, New York in 7 hours, 28 minutes. Despite its speed, Hughes was unable to sell the H-1 to the U.S. military.