The Phoenix Steel Company began in the late 18th century as a manufacturer of cut nails. It later became a major producer of railroad rails and iron and steel structural members. Claymont Division of the Phoenix Steel Corporation was established in 1960 when the company purchased the Claymont, Delaware steel plant from the Colorado Fuel and Iron Company. This small collection of materials originating from the Claymont steel plant includes miscellaneous plant announcements, catalogs, labor agreements, photographs, company-issued newsletters, and brief historical essays on the Phoenix Steel Corporation and its predecessors.

The Worth Steel Company was a manufacturer of steel plates in Claymont, Delaware. Its records consist of papers from its operations and from its predecessor companies (Viaduct Iron Works and Worth Brothers Company, both of Coatesville, Pennsylvania). Items include correspondence, accounts, datasheets, agreements, closing papers in sale to Colorado Fuel and Iron Corporation in 1951, and the sale of land in 1958.