{"nrhp_refnum":"86000021","name":"Coraopolis Bridge","other_names":[],"category":"structure","location":{"address":"Ohio River Back Channel at Ferree St. and Grand Ave.","address_restricted":false,"city":"Coraopolis","county":"Allegheny County","state":"PA","lat":40.51611219800003,"lon":-80.15177416999995,"geom_source":"nps_gis"},"listed_date":"1986-01-07","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Engineering","Transportation","Politics/Government"],"significance_levels":["national"],"summary":{"what_it_is":"A steel bowstring bridge crossing the back channel of the Ohio River, connecting the town of Coraopolis with the west end of Neville Island in Allegheny County, Pennsylvania. It was originally erected in 1892 as the third Sixth Street Bridge and moved to its present site in 1927.","why_significant":"The nomination argues the bridge is significant for its design by engineer Theodore Cooper, its age and unusual history of relocation, and its transportation role at two locations. Cooper is described as a nationally renowned bridge engineer, and the bridge is reported to be the only surviving work solely of his design.","narrative":"Steel bowstring bridge crossing the back channel of the Ohio River, linking Coraopolis with the west end of Neville Island. Built in 1892 as the third Sixth Street Bridge, linking Pittsburgh and Allegheny, it carried trolleys as well as vehicles. Its two main spans, each 445 feet, are riveted steel trusses resting on three concrete piers, with portal-like steel archways at the span ends. Cooper, a nationally renowned engineer who had worked on the Eads Bridge and the Brooklyn Bridge, was hired as consulting engineer, and Baird Brothers built it for $560,000. In 1919 the War Department ordered the older Allegheny River bridges replaced. The two main spans were floated down the Ohio on coal barges in 1927-28 and re-erected at Coraopolis, a move that took 140 days and cost $316,000. The bridge is regarded for its lacy girder design and for being the only surviving work of Cooper's design alone.","period_of_significance":"1881-1900","architect_builder":"Theodore Cooper (engineer); Baird Brothers (builder)","architectural_style":"Bowstring","criteria":[],"status_note":"Listed as part of a thematic group of Allegheny County-owned river bridges; present concrete deck carries two lanes of auto traffic.","vacant_flag":null,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:32.865177-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/86000021.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/86000021/3e1750fa62-800.webp","url_1600":"https://nationalhistoricalregister.com/media/86000021/3e1750fa62-1600.webp","licence":"Public domain","author":"The original uploader was Lar at English Wikipedia.","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:HAER_Coraopolis_04_356722pv.jpg\" rel=\"noopener\">The original uploader was Lar at English Wikipedia.</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:HAER_Coraopolis_04_356722pv.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71992228","wikipedia":null,"wikidata":"https://www.wikidata.org/wiki/Q60324845"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/allegheny-county/coraopolis-bridge-86000021/"}