{"nrhp_refnum":"80003410","name":"Merrill Lock No. 6","other_names":[],"category":"structure","location":{"address":"E of Midland on PA 68, Ohioview Township","address_restricted":false,"city":"Midland","county":"Beaver County","state":"PA","lat":40.668662823000034,"lon":-80.35144826299995,"geom_source":"nps_gis"},"listed_date":"1980-09-04","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Transportation","Architecture"],"significance_levels":["local"],"summary":{"what_it_is":"Merrill Lock No. 6 is a complex on the Ohio River at Midland, Beaver County, Pennsylvania, consisting of a power house flanked by two lockkeeper and crew houses, with the surviving bank wall of the lock. It was built between 1892 and 1904 as the second of ten locks and dams on the Ohio River.","why_significant":"The nomination argues the complex is significant in architecture, engineering and transportation. It is described as the only surviving lock and dam support buildings of this kind remaining on the Ohio River in Pennsylvania. The lock and dam system is presented as having allowed economical transport of goods between Pittsburgh and western markets along the Ohio and Mississippi rivers.","narrative":"Built of brick on concrete piles between 1892 and 1904, the Merrill Lock No. 6 complex on the Ohio River at Midland comprises a three-story power house with two nearly identical 2½-story lockkeeper and crew houses. The power house, which held machinery for the lock gates and water tanks in its tower, has deep brick arches, a slate roof on wood trusses and a cantilevered bay window giving views up and down the river. The lock was the second of ten built on the Ohio between Pittsburgh and Steubenville, and it entered operation in August 1904 with a nine-foot pool. The complex is regarded as the only surviving example of such dam and lock support buildings on the Ohio River in Pennsylvania. It was replaced by the Montgomery Lock and Dam in June 1936, after which the buildings were left vacant. The lock is associated with the canalization of the Ohio River and its role in regional freight transport.","period_of_significance":"1892-1904","architect_builder":null,"architectural_style":"Victorian with Richardsonian Romanesque influence","criteria":["A","C"],"status_note":"Abandoned and vacant since 1936; only the bank wall of the lock remains intact.","vacant_flag":true,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:32.856716-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/80003410.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/80003410/9043f10d12-800.webp","url_1600":"https://nationalhistoricalregister.com/media/80003410/9043f10d12-1600.webp","licence":"Public domain","author":"Nyttend","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Merrill_Lock_6_Landing.jpg\" rel=\"noopener\">Nyttend</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Merrill_Lock_6_Landing.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71996533","wikipedia":"https://en.wikipedia.org/wiki/Merrill_Lock_No._6","wikidata":"https://www.wikidata.org/wiki/Q1922027"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/beaver-county/merrill-lock-no-6-80003410/"}