During the war of 1812 America went through a very dodgy period. The British blockade of American ports effectively blocked imports of saltpeter and, hence, production of gunpowder. The upside of this was that it made the mininig of natural reserves of nitrates economically viable and the main beneficiary was the huge Mammoth Cave complex in Kentucky where the whole process of mining and production was carried out.
Significance: Mammoth Cave Saltpeter Works represent the most complete example known of the equipment used in the processing of cave saltpeter, a major component of gunpowder during the War of 1812. The works were constructed in their present form while under the ownership of Charles Wilkins of Lexington, Kentucky, and his partners, Fleming Gatewood of Warren County, Kentucky and Hyman Gratz of Philadelphia. The saltpeter manufactured here, perhaps as much as 115,000 pounds during 1814, was sole to eastern gunpowder manufacturers to meet American military needs. The works were abandoned about 1815, at the end of the war. Presently nine leaching vats, two collecting tanks, a portion of one pump, about fifty sections of wooden water pipe, and several pumptower timbers remain.
Source: HAER