{"nrhp_refnum":"77001203","name":"Tunkhannock Viaduct","other_names":["Nicholson Viaduct"],"category":"structure","location":{"address":"0.5 mi. E of Nicholson at Tunkhannock Creek","address_restricted":false,"city":"Nicholson","county":"Wyoming County","state":"PA","lat":41.623182350000036,"lon":-75.77662548862699,"geom_source":"nps_gis"},"listed_date":"1977-04-11","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Engineering","Transportation","Architecture"],"significance_levels":["national"],"summary":{"what_it_is":"A reinforced concrete railroad viaduct spanning Tunkhannock Creek near Nicholson, Wyoming County, Pennsylvania. It was built between 1912 and 1915 by the Lackawanna Railroad as part of a 39.6 mile cutoff between Clarks Summit and Halstead.","why_significant":"The nomination argues the viaduct was, when built, the largest concrete structure in the world and a pioneering example of reinforced concrete bridge construction of its size. It is described as an exemplar of its type and one of the most beautiful concrete bridges in America. Its arches and scale are presented as a landmark of early twentieth-century railroad modernization.","narrative":"Spanning Tunkhannock Creek near Nicholson in Wyoming County, Pennsylvania, this reinforced concrete railroad viaduct was built between 1912 and 1915 for the Lackawanna Railroad. It formed the centrepiece of a 39.6 mile cutoff between Clarks Summit and Halstead, part of a broader upgrade of the railroad's main line. The bridge is 2,375 feet long and rises 240 feet above the creek. Ten main semicircular arches of 180 feet span carry the deck, flanked by two 100-foot arches buried in the fill at either end. Each arch has two ribs, and the concrete was cast on steel falsework supported by an overhead cableway, whose centre tower reached 300 feet. Engineer Abraham Burton Cohen designed it. When completed it was the largest concrete structure in the world. The nomination regards it as a definitive example of its type, admired by critics and writers, and it is a longstanding landmark for the community.","period_of_significance":"1900-","architect_builder":"A.B. Cohen (engineer, Abraham Burton Cohen)","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 17:11:29.932998-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/77001203.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/77001203/2f055208c5-800.webp","url_1600":"https://nationalhistoricalregister.com/media/77001203/2f055208c5-1600.webp","licence":"Public domain","author":"WallyFromColumbia at English Wikipedia","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Steamtown-Nicholson-Viaduct.JPG\" rel=\"noopener\">WallyFromColumbia at English Wikipedia</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Steamtown-Nicholson-Viaduct.JPG"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71996784","wikipedia":"https://en.wikipedia.org/wiki/Tunkhannock_Viaduct","wikidata":"https://www.wikidata.org/wiki/Q7853242"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/wyoming-county/tunkhannock-viaduct-77001203/"}