Nitro, located on the Kanawha-Putnam line, was built during World War I to make smokeless powder (not nitroglycerin). The War Department hired a company to build the plant and town quickly, with 110,000 workers pouring in, including Clark Gable. The town had homes, a hospital, and a civic center, but the war ended before the plant was finished. After the war, the plant was sold and became home eventually to at least 17 companies. The Viscose Company started a plant in 1921 to make cotton linters for gunpowder. It became American Viscose, building the world’s largest rayon plant in 1937 (the world's largest by 1945), later called Avtex Fibers until 1980. Other companies in Nitro included Ohio Apex Chemical, Monsanto, Nitro Pencil Company, Nitro Soap Factory, and Fike Chemical.

Nitro’s population grew dramatically during this period but began declining, with the chemical industry, after 1980.