Powder Mill Valley along Cobbs Creek was for almost 200 years a center of manufacture. Early grist and saw mills were followed by fulling and dyeing mills. The Nitre Hall Powder Mills, which gave the valley its name, were built by Israel Whelen shortly after 1800. Our young nation had growing needs for explosives and the mills prospered with an output of 800,000 pounds during the war of 1812. Nitre Hall Mills produced a quality and quantity of black powder in the U.S. second only to the Dupont Mills on the Brandywine. After the powder mills closed in 1840, Dennis Kelly bought the property and converted the buildings to the manufacture of textiles.
Nitre Hall, the home of the powder master, is the only building remaining from the industrial era of the valley. The brick floored ground level was converted to an apartment for caretakers in the 1980's. No one currently lives in Nitre Hall, and work has been done to restore this area to it's original layout. The parlor on the 2nd floor level is furnished in Empire style. Across the hall is the Historical Society Library with reference books and Materials on the history of Haverford Township. Furnishings in this room are Victorian. Rooms on the third floor are used for exhibits that are changed periodically. A large room is also used as a class room for the Colonial Living Experience.
Nitre Hall is on the National Register of Historic Places. Buildings are open to the public May through October on a scheduled basis, in December for special events, and by appointment.