{"nrhp_refnum":"75002075","name":"Ellwood Mansion","other_names":[],"category":"building","location":{"address":"509 N. 1st St.","address_restricted":false,"city":"De Kalb","county":"DeKalb County","state":"IL","lat":41.93511117150007,"lon":-88.75244523914124,"geom_source":"nps_gis"},"listed_date":"1975-06-13","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Industry"],"significance_levels":["national"],"summary":{"what_it_is":"A historic estate at 509 North First Street in De Kalb, Illinois, centered on a brick mansion built in 1879 for barbed wire manufacturer Isaac Ellwood, with a water tower, carriage house, museum house and a small stick-style house. Five of the original nine structures survive.","why_significant":"The property is tied to Isaac Ellwood, who organized the barbed wire industry, which was critical to agricultural development of the Trans-Mississippi West. Ellwood was also a civic leader who helped bring the state normal college, now Northern Illinois University, to De Kalb. The house is described as a monument to the barbed wire industry and to his contributions to De Kalb and the nation.","narrative":"Ellwood House in De Kalb, Illinois, is an estate built around a three-story brick mansion with a mansard roof, completed in 1879 for Isaac Ellwood at a cost of $50,000. Chicago architect George O. Garnsey designed it. Ellwood altered the facade in 1899, and his son E. Perry Ellwood ordered extensive changes in 1910, including new verandas and the removal of a corner tower. Five of nine original structures remain: the house, a limestone water tower, a carriage house built for automobiles, a museum house of 1905, and a miniature stick-style house built in 1892 for a parade float. Isaac Ellwood partnered with Joseph Glidden in barbed wire manufacture and became a leading figure in organizing the industry, which shaped agriculture in the American West. He also helped secure De Kalb as the site of the state normal college. His family donated the home and grounds to the city in 1964, and the house now operates as a museum.","period_of_significance":"19th Century; specific dates 1879 and 1910","architect_builder":"George O. Garnsey of Chicago (original 1879 architect); Perkins, Fellows, and Hamilton of Chicago (1910 remodelling); George Terwilliger of Marshall Field (interior decorator); Joseph Dux (fireplace mantel carver)","architectural_style":null,"criteria":[],"status_note":"Owned by the De Kalb Park District and maintained as a museum and park; condition rated excellent, with preservation work in progress on the museum house.","vacant_flag":false,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:55:35.921377-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/opastorage/live/30/8927/28892730/content/electronic-records/rg-079/NPS_IL/75002075.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/75002075/b9f0e4e675-800.webp","url_1600":"https://nationalhistoricalregister.com/media/75002075/b9f0e4e675-1600.webp","licence":"CC0","author":"Paul R. Burley","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Ellwood_House_DeKalb_Illinois_2022-6682.jpg\" rel=\"noopener\">Paul R. Burley</a>, <a href=\"http://creativecommons.org/publicdomain/zero/1.0/deed.en\" rel=\"license noopener\">CC0</a>, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Ellwood_House_DeKalb_Illinois_2022-6682.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/28892730","wikipedia":"https://en.wikipedia.org/wiki/Ellwood_House","wikidata":"https://www.wikidata.org/wiki/Q5366195"},"indexable":true,"url":"https://nationalhistoricalregister.com/illinois/dekalb-county/ellwood-mansion-75002075/"}