{"nrhp_refnum":"88000779","name":"McClay's Twin Bridge (West)","other_names":["McClay's Bridge (East)"],"category":"structure","location":{"address":"LR 28010 over Conodoguinet Creek","address_restricted":false,"city":"Middle Spring","county":"Franklin County","state":"PA","lat":40.09818085000006,"lon":-77.56960912599999,"geom_source":"nps_gis"},"listed_date":"1988-06-22","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Engineering"],"significance_levels":["state"],"summary":{"what_it_is":"A multiple-span stone camelback turnpike bridge carrying vehicular traffic across Conodoguinet Creek in Franklin County, Pennsylvania, between Southampton and Lurgan Townships. It was built in 1827 by master mason Silas Harry as one of two adjoining bridges on the same road.","why_significant":"The nomination describes it as a very fine example of a long, multiple-span nineteenth-century turnpike bridge. Its roughly coursed local limestone, semi-pyramidal piers and coping are presented as typical of Franklin County bridges built before 1860. Silas Harry is described as one of Pennsylvania's master masons who built stone bridges along the National Road in Pennsylvania and Maryland. The area of significance is engineering.","narrative":"Built in 1827 by Silas Harry, a Pennsylvania master mason, this three-arch stone bridge crosses Conodoguinet Creek between Southampton and Lurgan Townships in Franklin County. It measures about 177 feet overall, with a central arch of 31 feet and two flanking arches of 29 feet each. Its wings curve outward and widen at the approaches, and its stone parapet has a concrete cap. A second bridge stands alongside it on the same road, and the two are commonly known as McClay's Twin Bridges. Harry also built stone bridges along the National Road in Pennsylvania and Maryland. The bridge is valued as a very fine example of a long, multiple-span turnpike bridge from the early nineteenth century. Its roughly coursed local limestone, semi-pyramidal piers and coping reflect construction methods typical of Franklin County bridges built before 1860. Few stone bridges from that county survive, which adds to its importance. The structure was altered in 1982 but retains its essential character.","period_of_significance":"1827","architect_builder":"Silas Harry (builder/contractor)","architectural_style":"Camelback","criteria":[],"status_note":"Altered in 1982; the document describes the appearance as slightly altered.","vacant_flag":null,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:35.895737-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/88000779.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/88000779/8f3c692a9c-800.webp","url_1600":"https://nationalhistoricalregister.com/media/88000779/8f3c692a9c-1600.webp","licence":"Public domain","author":"Joseph Elliott, Photographer","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Maclay%27s_Mill_Twin_Bridge_(East_%26_West),_Spanning_Conodoguinet_Creek_at_Maclay%27s_Mill_Road_,_Mowersville_vicinity_(Franklin_County,_Pennsylvania).jpg\" rel=\"noopener\">Joseph Elliott, Photographer</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Maclay%27s_Mill_Twin_Bridge_(East_%26_West),_Spanning_Conodoguinet_Creek_at_Maclay%27s_Mill_Road_,_Mowersville_vicinity_(Franklin_County,_Pennsylvania).jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71992959","wikipedia":"https://en.wikipedia.org/wiki/McClay%27s_Twin_Bridge_(West)","wikidata":"https://www.wikidata.org/wiki/Q6800293"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/franklin-county/mcclays-twin-bridge-west-88000779/"}