{"nrhp_refnum":"80003544","name":"McConnell's Mill Covered Bridge","other_names":[],"category":"structure","location":{"address":"N of Portersville on T 415, Slippery Rock Township","address_restricted":false,"city":"Princeton","county":"Lawrence County","state":"PA","lat":40.95289037500004,"lon":-80.17021313599997,"geom_source":"nps_gis"},"listed_date":"1980-06-27","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Engineering","Transportation"],"significance_levels":["state"],"summary":{"what_it_is":"A covered bridge over Slippery Rock Creek in Lawrence County, Pennsylvania, located in Slippery Rock Township, built in 1874. It is a Howe truss structure measuring 96.5 feet end post to end post, 15 feet wide, with 10 feet of clearance.","why_significant":"The bridge is one of four remaining covered bridges in Pennsylvania that use the Howe truss, and it is the longest of those four. The document also notes it is one of only two covered bridges remaining in Lawrence County, and that it is in good condition with a gable roof, vertical plank siding and no window openings.","narrative":"Spanning Slippery Rock Creek in Slippery Rock Township, Lawrence County, this covered bridge was built in 1874. It carries a Howe truss, a timber framing system in which vertical posts and diagonal iron rods work together to bear the load. The structure measures 96.5 feet from end post to end post and 15 feet wide, with 10 feet of vertical clearance and a rated load of 5 tons. Its gable roof and vertical plank siding enclose the span, and it has no window openings. The nomination counts it among four surviving Pennsylvania covered bridges using the Howe truss, and the longest of those four. It is also one of only two covered bridges remaining in Lawrence County. Recorded as being in good condition, the bridge was listed as part of a county thematic group of covered bridges, which documents the regional survival of this type of construction.","period_of_significance":null,"architect_builder":null,"architectural_style":null,"criteria":[],"status_note":"Condition recorded as good.","vacant_flag":null,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:34.354611-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/80003544.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/80003544/2b47d38a4a-800.webp","url_1600":"https://nationalhistoricalregister.com/media/80003544/2b47d38a4a-1600.webp","licence":"Public domain","author":"Nyttend","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:McConnell%27s_Mill_Covered_Bridge_northern_side_in_sunlight.jpg\" rel=\"noopener\">Nyttend</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:McConnell%27s_Mill_Covered_Bridge_northern_side_in_sunlight.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71993307","wikipedia":"https://en.wikipedia.org/wiki/McConnell%27s_Mill_Covered_Bridge","wikidata":"https://www.wikidata.org/wiki/Q1915040"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/lawrence-county/mcconnells-mill-covered-bridge-80003544/"}