The bulk of the "X" files are also the 1951 to 1962 counterparts of the patent and licensing files. In addition, file X-536 has material relating to a new dynamite plant in the Philippines, relations with Latin American subsidiaries, and a notice of discontinuing information exchanges with the Axis countries in the summer of 1941. File X-552 describes the company's response to tariffs and reciprocal trade agreements (1935-1956). File X-918 describes a project to build a powder plant in Chile (1914-1922). File X-1014 contains authorizations to apply for trademarks for DuPont products, both successful and unsuccessful (1917-1962). File X-1029 contains additional reports of the International Freighting Corporation, and File X-879 contains reports from Nobel Industries Ltd. and Nobel Explosives Co., Ltd.

The earliest files describe the merger of most of the nation's powder companies into the E.I. du Pont de Nemours Powder Company in 1903. Other important subjects of the 1903 to 1921 period include the proposed purchase of the American operations of Bayer, illustrated reports on growing camphor in Florida, the purchase of the Winchester Repeating Arms Co., the need for more employee housing in Wilmington, the formation of the DuPont Chemical Co. to dismantle former war plants, and the steps leading to the abandonment of the original Brandywine Works.

File X-919 contains testimony of Irénée du Pont and Morris R. Porcher before a 1922 Senate subcommittee investigating monopoly in the dyestuffs industry and a 1926 Public Health Service report on tetraethyl lead. There is information on employee incentives such as bonus, life insurance, and profit-sharing plans, as well as notices from the National Civic Federation, and safety notices and statistics.

File X-984 includes an interesting account of the attempt of General Motors to develop a joint venture in the Soviet Union. A 1930 report assesses economic and political conditions in the period of Stalin's first Five Year Plan. File X-381 contains Walter Dorwin Teague's presentation book for the design of the DuPont Pavilion at the 1939 World's Fair. File X-1040 contains the first announcement to the stockholders of the discovery of nylon, and there is also an illustrated report on the town of Seaford, Delaware, showing the impact of the nylon plant there. Another report describes the state of the Cuban sugar cane industry. The files also include a memorial of Edmond Grillet of Comptoir Textiles Artificiels and a copy of the will of James B. Duke.