{"nrhp_refnum":"78002398","name":"Dunlap's Creek Bridge","other_names":["First Cast Iron Bridge in America"],"category":"structure","location":{"address":"Spans Dunlap","address_restricted":false,"city":"Brownsville","county":"Fayette County","state":"PA","lat":40.02134816000006,"lon":-79.88828550699998,"geom_source":"nps_gis"},"listed_date":"1978-07-31","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Engineering","Transportation","Invention"],"significance_levels":["national"],"summary":{"what_it_is":"A single-span cast iron bridge carrying the National Road over Dunlap's Creek at Brownsville in Fayette County, Pennsylvania, built 1836-1839 with an 80-foot arch. It is described as the first cast iron bridge in America.","why_significant":"The nomination argues the bridge is significant as a farsighted engineering solution to the arch thrust problem that stone abutments could not resist, and as an early durable use of cast and wrought iron. Its iron was tested in 1921 and found to have deteriorated very little. It was also the last work on the Cumberland Road east of the Ohio River funded by Congress.","narrative":"Spanning Dunlap's Creek on the National Road at Brownsville, Pennsylvania, this single-span bridge was built between 1836 and 1839 from designs prepared under Captain Richard Delafield. It has an 80-foot cast iron arch built from hollow curved ribs, with sandstone abutments and wrought iron railings. Earlier crossings at the site were a wooden bridge destroyed by flood in 1808, a chain-suspended bridge that collapsed in 1820, and a timber bridge. Delafield chose iron because local stone could not resist the outward thrust of an arch of this span, and wood was vulnerable to decay and fire. Its iron was tested in 1921 and found to have deteriorated very little. Concrete decking and I-beam supports were added later, but the original arch remains largely unchanged. The bridge was completed in 1839 and was the final Congressionally funded work on the Cumberland Road east of the Ohio.","period_of_significance":"1836-1839","architect_builder":"Richard Delafield (architect)","architectural_style":null,"criteria":[],"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 17:11:30.886846-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/78002398.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/78002398/11b5868e68-800.webp","url_1600":"https://nationalhistoricalregister.com/media/78002398/11b5868e68-1600.webp","licence":"Public domain","author":"Jet Lowe","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Dunlap_creek_bridge_jet_lowe_1983.jpg\" rel=\"noopener\">Jet Lowe</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Dunlap_creek_bridge_jet_lowe_1983.jpg"},"district":{"nrhp_refnum":"93000716","name":"Brownsville Commercial Historic District","url":"https://nationalhistoricalregister.com/districts/pennsylvania/brownsville-commercial-historic-district-93000716/"},"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71994803","wikipedia":"https://en.wikipedia.org/wiki/Dunlap%27s_Creek_Bridge","wikidata":"https://www.wikidata.org/wiki/Q5315401"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/fayette-county/dunlaps-creek-bridge-78002398/"}