{"nrhp_refnum":"00000400","name":"Allegheny River Lock and Dam No. 6","other_names":[],"category":"structure","location":{"address":"1258 River Rd.","address_restricted":false,"city":"Freeport","county":"Armstrong County","state":"PA","lat":40.718144878500055,"lon":-79.57911620728356,"geom_source":"nps_gis"},"listed_date":"2000-04-21","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Transportation","Maritime History","Architecture","Engineering"],"significance_levels":["state"],"summary":{"what_it_is":"A U.S. Army Corps of Engineers navigation complex on the Allegheny River in Freeport, Armstrong County, Pennsylvania, comprising a lock, a fixed-crest dam, an esplanade, an operations building (powerhouse) and two locktenders' houses. The Corps constructed it in 1927-1928 about 36.3 miles upstream from the river's mouth.","why_significant":"The nomination argues the lock and dam are significant under Criterion A as part of the integral slackwater system that gave commercial barge access to 72 miles of the Allegheny River, including access to the Pittsburgh Plate Glass mills at Ford City. It also argues Criterion C significance as a representative example of lock and dam construction of 1927-1928 that retains its original appearance, machinery and function.","narrative":"Built on the west bank of the Allegheny River about 36 miles upstream from its mouth, this lock and dam complex was constructed by the U.S. Army Corps of Engineers in 1927-1928. The lock measures 56 by 360 feet and lifts vessels 12.4 feet. Its 992-foot fixed-crest dam, roughly 20 feet high, rests on timber piles and stone-filled cribbing, with the dam portion built by Dravo Corporation. A two-story operations building houses hydraulic pumps driven by water turbines, which operated the lock's gates and valves. Two identical two-story tan brick locktenders' houses stand on the site. The facility opened on October 10, 1928, and formed part of a slackwater system giving commercial barges access to 72 miles of the river, including the Pittsburgh Plate Glass mills at Ford City. It is also valued as a well-preserved example of lock and dam construction from this period, retaining much of its original machinery and layout.","period_of_significance":"1903-1938","architect_builder":"Dam - Dravo Corporation; Lock - Corps of Engineers","architectural_style":"Late Nineteenth and Early Twentieth Century Revival","criteria":["A","C"],"status_note":"Lock and dam remain in operation; the modern hydroelectric plant on the east side was added in 1988 and the operations building's original windows have been replaced; the locktenders' houses are presently vacant.","vacant_flag":null,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:36.047284-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/00000400.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/00000400/aca1f5e2ee-800.webp","url_1600":"https://nationalhistoricalregister.com/media/00000400/aca1f5e2ee-1600.webp","licence":"CC BY-SA 3.0","author":"Generic1139","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Allegheny_River_Locktenders_House.jpg\" rel=\"noopener\">Generic1139</a>, <a href=\"https://creativecommons.org/licenses/by-sa/3.0\" rel=\"license noopener\">CC BY-SA 3.0</a>, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Allegheny_River_Locktenders_House.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71992250","wikipedia":"https://en.wikipedia.org/wiki/Allegheny_River_Lock_and_Dam_No._6","wikidata":"https://www.wikidata.org/wiki/Q4731339"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/armstrong-county/allegheny-river-lock-and-dam-no-6-00000400/"}