{"nrhp_refnum":"06001070","name":"Carrie Blast Furnace Number 6 and 7","other_names":[],"category":"district","location":{"address":"North side of Monongahela River .5 mi west of Rankin Bridge","address_restricted":false,"city":"Rankin, Munhall, Swissvale boroughs","county":"Allegheny County","state":"PA","lat":40.41387179800006,"lon":-79.88972793299996,"geom_source":"nps_gis"},"listed_date":"2006-09-20","is_nhl":true,"nhl_designated_date":"2006-09-20","areas_of_significance":[],"significance_levels":["national"],"summary":{"what_it_is":"Two pre-World War II blast furnaces, Carrie Blast Furnaces Numbers 6 and 7, and related ironmaking resources on the north bank of the Monongahela River in the boroughs of Rankin, Munhall and Swissvale, Allegheny County, Pennsylvania, together with the Hot Metal Bridge to the former Homestead Steel Works.","why_significant":"The nomination argues the furnaces are the only remaining pre-World War II blast furnaces in the Pittsburgh District and among few in the United States that retain much of their original equipment. It states they are exceptional examples of integrated 'Northern' or 'Mesabi' practice ironmaking, and that their technology and role in the industrial economy make them nationally significant in engineering and industry.","narrative":"Carrie Blast Furnaces Numbers 6 and 7 are two steel-frame iron-producing stacks on the north bank of the Monongahela River, a short distance east of Pittsburgh, in the boroughs of Rankin, Munhall and Swissvale. Built in 1906-1907, they formed part of the integrated Carrie plant that supplied basic iron to the open-hearth furnaces of the Homestead Steel Works from 1907 to 1978. The furnaces operated as a pair, sharing ore storage, hot blast stoves, blowing engines and gas-processing equipment. Their gas was cleaned and used to fire boilers and generate electricity for the mill. Most of the original equipment dates from the 1920s to the 1940s, a level of integrity uncommon among furnaces built before World War I. The district also includes the Hot Metal Bridge, built in 1900-1901, which carried molten iron across the river. The property is significant for its engineering and its role in industrial production.","period_of_significance":"1906-1941","architect_builder":null,"architectural_style":"No Style","criteria":["A","C"],"status_note":"Carrie 6 and 7 remain standing as a district of twenty-seven resources; the rest of the Carrie plant has been torn down and access to the site was limited during study.","vacant_flag":null,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:30.423285-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/06001070_NHL.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/06001070/f6600f9545-800.webp","url_1600":"https://nationalhistoricalregister.com/media/06001070/f6600f9545-1600.webp","licence":"Public domain","author":"PixOnTrax at English Wikipedia","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Carrie_Furnace030.jpg\" rel=\"noopener\">PixOnTrax at English Wikipedia</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Carrie_Furnace030.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71994401","wikipedia":"https://en.wikipedia.org/wiki/Carrie_Furnace","wikidata":"https://www.wikidata.org/wiki/Q5046232"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/allegheny-county/carrie-blast-furnace-number-6-and-7-06001070/"}