{"nrhp_refnum":"71000523","name":"Whipple Cast and Wrought Iron Bowstring Truss Bridge","other_names":[],"category":"structure","location":{"address":"1000 Delaware Ave.","address_restricted":false,"city":"Albany","county":"Albany County","state":"NY","lat":42.63574881000005,"lon":-73.80065539699996,"geom_source":"nps_gis"},"listed_date":"1971-03-18","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Commerce","Engineering","Transportation","Invention"],"significance_levels":["state"],"summary":{"what_it_is":"A 109-foot, 10-inch cast- and wrought-iron bowstring truss bridge at Normanskill Farm, 1000 Delaware Avenue, Albany, New York. It was fabricated in 1867 by Simon DeGraft of Syracuse and re-erected at the farm in 1899.","why_significant":"The bridge is a surviving example of the Whipple bowstring truss, designed by Squire Whipple, one of the earliest civil engineers to develop a scientific basis for American bridge building. It is described as one of the earliest surviving iron bridges in the United States and a key landmark in American civil engineering history. It is still in use as the farm's main entrance.","narrative":"Spanning a deep ravine at Normanskill Farm in Albany, this iron bridge is a Whipple bowstring truss with a free span of 109 feet, 10 inches. Each top chord is an arch of nine cast-iron segments working in compression, while wrought-iron links in the bottom chords restrain the arch's outward thrust. Sixteen vertical iron rods carry the load upward, and a deck of iron beams supports diagonal wood planking. Simon DeGraft of Syracuse fabricated it in 1867, and its original location is unknown. When the Albany and Delaware Turnpike, now Delaware Avenue, was rerouted in 1899, the farm bought the bridge and re-erected it over the ravine separating the property from the new highway. The design came from Squire Whipple, who patented his iron bowstring truss in 1841. The bridge is regarded as one of the earliest surviving iron bridges in the United States and remains the farm's main entrance.","period_of_significance":"19th Century (specific date 1867)","architect_builder":"Simon DeGraft of Syracuse, New York (builder); Whipple truss design by Squire Whipple","architectural_style":null,"criteria":[],"status_note":"Described as well maintained, in good condition, and still serving as the main entrance to Normanskill Farm.","vacant_flag":false,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:50:39.24057-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_NY/71000523.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/71000523/a3d66c2c25-800.webp","url_1600":"https://nationalhistoricalregister.com/media/71000523/a3d66c2c25-1600.webp","licence":"CC BY-SA 2.0","author":"Doug Kerr from Albany, NY, United States. Cropped and edited slightly by Daniel Case prior to upload","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Normanskill_Farm_Bridge,_Albany,_NY,_deck_view_from_west.jpg\" rel=\"noopener\">Doug Kerr from Albany, NY, United States. Cropped and edited slightly by Daniel Case prior to upload</a>, <a href=\"https://creativecommons.org/licenses/by-sa/2.0\" rel=\"license noopener\">CC BY-SA 2.0</a>, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Normanskill_Farm_Bridge,_Albany,_NY,_deck_view_from_west.jpg"},"district":{"nrhp_refnum":"100003625","name":"Normanskill Farm","url":"https://nationalhistoricalregister.com/districts/new-york/normanskill-farm-100003625/"},"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/75316383","wikipedia":"https://en.wikipedia.org/wiki/Whipple_Cast_and_Wrought_Iron_Bowstring_Truss_Bridge","wikidata":"https://www.wikidata.org/wiki/Q7993745"},"indexable":true,"url":"https://nationalhistoricalregister.com/new-york/albany-county/whipple-cast-and-wrought-iron-bowstring-truss-bridge-71000523/"}