{"nrhp_refnum":"88000848","name":"Hogback Bridge","other_names":["Porter Bridge"],"category":"structure","location":{"address":"LR 869 over W branch of Susquehanna River","address_restricted":false,"city":"Curwensville","county":"Clearfield County","state":"PA","lat":40.973591455000076,"lon":-78.49039344699997,"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":"Hogback Bridge is a single-span pin-connected Pennsylvania (Petit) pony truss highway bridge over the West Branch Susquehanna River near Curwensville in Clearfield County, Pennsylvania. It was built in 1893 by the King Bridge Company of Cleveland, Ohio.","why_significant":"The nomination describes the bridge as an intact, very well preserved example of a commonly used Pennsylvania truss design. It also presents the bridge as an example of the work of a leading nineteenth-century manufacturer of metal truss bridges. It is one of eight Pennsylvania truss bridges included in a multiple-resource nomination, and its significance is placed in the area of engineering.","narrative":"Built in 1893 over the West Branch of the Susquehanna River near Curwensville, Clearfield County, Hogback Bridge is a single 215-foot span of the Pennsylvania truss type, a pin-connected pony truss with a full-slope half-hip profile and steel eyebars. It was fabricated by the King Bridge Company of Cleveland, Ohio, which was known as King Iron Bridge and Manufacturing Company from 1871 to 1893 and built bridges into the early twentieth century. The bridge is regarded as a very well preserved example of a design that was widely used in Pennsylvania. It is also notable as the work of a leading American maker of metal truss bridges. The structure carries vehicular traffic on a steel superstructure resting on stone abutments and wing walls. Its nomination is part of a group of eight Pennsylvania truss bridges owned by the state transportation department, recognized for both their engineering character and their manufacturer.","period_of_significance":"1893","architect_builder":"King Bridge Company (Cleveland, Ohio), bridge manufacturer","architectural_style":null,"criteria":["C"],"status_note":null,"vacant_flag":false,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:35.853719-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/88000848.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/88000848/448c244e2a-800.webp","url_1600":"https://nationalhistoricalregister.com/media/88000848/448c244e2a-1600.webp","licence":"Public domain","author":"PennDOT","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Hogback_Bridge.jpg\" rel=\"noopener\">PennDOT</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Hogback_Bridge.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71992782","wikipedia":"https://en.wikipedia.org/wiki/Hogback_Bridge","wikidata":"https://www.wikidata.org/wiki/Q5877139"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/clearfield-county/hogback-bridge-88000848/"}