{"nrhp_refnum":"88000812","name":"Charleroi-Monessen Bridge","other_names":[],"category":"structure","location":{"address":"LR 247 over Monongahela River","address_restricted":false,"city":"Charleroi","county":"Washington County","state":"PA","lat":40.15186240100007,"lon":-79.90388999999999,"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 steel truss and deck girder highway bridge carrying vehicles across the Monongahela River between Charleroi and Monessen in Washington County, Pennsylvania. It was built in 1906 by the Mercantile Bridge Company.","why_significant":"The nomination describes it as a good example of a multiple-span Pennsylvania (Petit) truss bridge. It combines three longer Pennsylvania truss spans with thirteen deck girder spans, making it one of the longest bridges in its thematic group. It lies in southwestern Pennsylvania, an area with a heavy concentration of truss bridges, and its significance is placed under engineering.","narrative":"Built in 1906 by the Mercantile Bridge Company from a design by engineer Emil Swensson, the Charleroi-Monessen Bridge carries vehicular traffic across the Monongahela River, connecting the town of Charleroi with factories on the opposite bank. It is a steel structure with three Pennsylvania (Petit) truss spans of about 400 feet each, the anchor span among them, and thirteen deck girder spans. The total length is about 2,458 feet. The truss spans are pin-connected and riveted, with loop-welded or die-forged eyebars, and the abutments are coursed ashlar. The bridge is regarded as a good example of its type. Its combination of long truss spans and a large number of girder approaches made it one of the longest bridges in its group. Its location in southwestern Pennsylvania, an area with many truss bridges, adds to its importance in the state's engineering history.","period_of_significance":"1906","architect_builder":"Emil Swensson (engineer); Mercantile Bridge Company (bridge company)","architectural_style":null,"criteria":["C"],"status_note":null,"vacant_flag":null,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:36.285605-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/88000812.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/88000812/a72e4d30ce-800.webp","url_1600":"https://nationalhistoricalregister.com/media/88000812/a72e4d30ce-1600.webp","licence":"Public domain","author":"VitaleBaby at Wikipedia","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Newcharleroimonessen.jpeg\" rel=\"noopener\">VitaleBaby at Wikipedia</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Newcharleroimonessen.jpeg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71994053","wikipedia":"https://en.wikipedia.org/wiki/Charleroi%E2%80%93Monessen_Bridge","wikidata":"https://www.wikidata.org/wiki/Q5074682"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/washington-county/charleroi-monessen-bridge-88000812/"}