The U.S. Nitrate Plant Collection includes photographs of the construction, employee housing, and support facilities of U.S. Nitrate Plant No. 2 in the Muscle Shoals, AL area. In need of nitrates during World War I, in 1917 President Woodrow Wilson approved the building of two nitrate plants and a dam to supply needed electricity for the plants. The result was the construction of Wilson Dam and two nitrate plants. Sheffield, AL was chosen as the site for U.S. Nitrate Plant No. 1 where a German nitrate manufacturing process was to be tested; the nearby Muscle Shoals area was chosen for U.S. Nitrate Plant No. 2 that would experiment with the American Cynamid process. During construction the worker population rose from around 300 in January 1818 to nearly 21,000 in August 1918. Plant No. 1 was closed when the tested manufacturing method proved to be flawed; Plant No. 2 went into production on November 25, 1918. Since the armistice ending WWI had been signed on November 11, production was no longer considered necessary and the facilities were left idle.