{"nrhp_refnum":"70000545","name":"Nitre Hall","other_names":[],"category":"building","location":{"address":"Karakung Dr.","address_restricted":false,"city":"Haverford","county":"Delaware County","state":"PA","lat":39.983657169000026,"lon":-75.28551928399997,"geom_source":"nps_gis"},"listed_date":"1970-12-18","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Industry","Commerce","Architecture"],"significance_levels":["national"],"summary":{"what_it_is":"Nitre Hall is a four-storey stone mansion house in Haverford Township, Delaware County, Pennsylvania, built shortly after 1800 as the residence of the powder master of the Nitre Hall gunpowder mill complex on Cobb Creek. It is the mansion house and the surviving exterior walls of the stone powder magazine that remain from the complex.","why_significant":"The nomination argues that the Nitre Hall gunpowder mills were an important producer of powder for military, hunting, mining and engineering uses and a major contributor to the opening of the West, second only to the DuPont company near Wilmington. The house is significant for its largely unaltered interior and its Federal-type trim and neo-classical stair balusters, and the surviving powder magazine is also part of the story of the mills.","narrative":"Built on Cobb Creek in Haverford Township shortly after 1800, Nitre Hall is a four-storey stone mansion that served as the residence of the powder master of a gunpowder mill complex. The mills included a refinery, a charcoal willow house, stamping and press mills, a testing house and a powder magazine, and the works supplied powder for military, hunting, mining and engineering uses. Built by Israel Whelen, the operation later passed to William Rogers Jr. and then to Dennis Kelly, and it competed closely with the DuPont company near Wilmington. Explosions destroyed mill buildings in 1825 and 1831, and the business declined after 1825 and closed after the owner's death around 1839 or 1840. The house is valued for its interior, which remains largely unchanged, with Federal-style window and mantel trim and neo-classical urn-shaped stair balusters. Its stone powder magazine survives as the only remaining mill building, and the house is among the few tangible remains of the early American powder industry in the region.","period_of_significance":"c. 1805-1810","architect_builder":null,"architectural_style":"Federal type trim; neo-classical influence in stair balusters","criteria":["A","C"],"status_note":"Virtually unchanged on the interior; exterior restored in 1861, roof replaced in 1959, painted in 1960 and plastered in 1961; used as a private residence after 1839.","vacant_flag":null,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:30.267497-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/70000545.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/70000545/b1406a9ba0-800.webp","url_1600":"https://nationalhistoricalregister.com/media/70000545/b1406a9ba0-1600.webp","licence":"Public domain","author":"User:Smallbones on English Wikipedia.","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:NitreHall.JPG\" rel=\"noopener\">User:Smallbones on English Wikipedia.</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:NitreHall.JPG"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71995841","wikipedia":"https://en.wikipedia.org/wiki/Nitre_Hall","wikidata":"https://www.wikidata.org/wiki/Q7041385"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/delaware-county/nitre-hall-70000545/"}