{"nrhp_refnum":"94001187","name":"Staple Bend Tunnel","other_names":["Allegheny Portage Railroad Tunnel"],"category":"structure","location":{"address":"Jct. of PA 3035 and Mineral Pt.","address_restricted":false,"city":"Conemaugh Township","county":"Cambria County","state":"PA","lat":40.35939365300004,"lon":-78.85502036189823,"geom_source":"nps_gis"},"listed_date":"1994-04-19","is_nhl":true,"nhl_designated_date":"1994-04-19","areas_of_significance":["Transportation","Engineering"],"significance_levels":["national"],"summary":{"what_it_is":"The Staple Bend Tunnel is a sandstone railroad tunnel on a bend of the Little Conemaugh River in Conemaugh Township, Cambria County, Pennsylvania. It carried the Allegheny Portage Railroad through about 900 feet of rock.","why_significant":"The nomination argues the tunnel was the first railroad tunnel in the United States and an engineering achievement of its time. It also links the tunnel to regional trade, helping keep Philadelphia a major port by connecting it with western Pennsylvania. Its national significance is tied to the history of tunneling.","narrative":"Built between 1831 and 1833 on the Allegheny Portage Railroad in Conemaugh Township, Cambria County, Pennsylvania, the Staple Bend Tunnel runs about 900 feet through sandstone and shale beside a bend of the Little Conemaugh River. Sylvester Welch served as chief engineer, and J. and E. Appleton built it. Its horseshoe-shaped opening is about 20 feet wide and 16 feet tall at the crown. The first 150 feet at each end are lined with dressed stone, while the central 600 feet remain unlined rock marked by original drill-hole scars. Workers drilled by hand and blasted with black powder, and the tunnel was taken out of use in the 1850s. It is regarded as the first railroad tunnel in the United States. It also shows how the railroad carried canal boats over the Allegheny Mountain, linking Philadelphia with Pittsburgh at a time when trade was moving away from the Ohio and Mississippi rivers. Its construction methods and engineering reflect early American tunnel practice.","period_of_significance":"1831-1853","architect_builder":"Sylvester Welch (Chief Engineer) / J. & E. Appleton (Builders)","architectural_style":null,"criteria":["A","C"],"status_note":"The eastern portal has suffered the greatest damage since the tunnel was taken out of use in the 1850s, and both portals are now sealed with concrete block walls and steel doors. The National Park Service is negotiating to purchase the tunnel, which is not open to visitors.","vacant_flag":null,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:30.522301-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/94001187_NHL.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/94001187/dea5534c7d-800.webp","url_1600":"https://nationalhistoricalregister.com/media/94001187/dea5534c7d-1600.webp","licence":"Public domain","author":null,"credit_html":"Unknown author, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Allegheny_Portage_Railroad,_Staple_Bend_Tunnel,_East_of_Cambria_Railroad_Bridge_(Conemaugh_Township),_Geistown,_Cambria_County,_PA_HABS_PA,11-GEITO.V,1-_(sheet_1_of_2).tif"},"district":{"nrhp_refnum":"66000648","name":"Allegheny Portage Railroad National Historic Site","url":"https://nationalhistoricalregister.com/districts/pennsylvania/allegheny-portage-railroad-national-historic-site-66000648/"},"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71994171","wikipedia":"https://en.wikipedia.org/wiki/Staple_Bend_Tunnel","wikidata":"https://www.wikidata.org/wiki/Q7482493"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/cambria-county/staple-bend-tunnel-94001187/"}