{"nrhp_refnum":"01000519","name":"Locomotive No. 6755","other_names":["Class M1b, Mountain Type"],"category":"structure","location":{"address":"E. of Stasburg","address_restricted":false,"city":"Strasburg","county":"Lancaster County","state":"PA","lat":39.982416870000066,"lon":-76.16077163499995,"geom_source":"nps_gis"},"listed_date":"1979-12-17","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Commerce","Transportation"],"significance_levels":["national"],"summary":{"what_it_is":"Pennsylvania Railroad Class Mlb Mountain-type steam locomotive No. 6755, a 4-8-2 built in 1930, held in Strasburg, Lancaster County, Pennsylvania. It is part of the Pennsylvania Railroad Rolling Stock thematic resource.","why_significant":"The nomination argues the locomotive is the only surviving example of its class. The Mountain type was a dual-service engine, and the class was used heavily on freight work in its later years. The listing is part of a group of rolling stock that together represents historically significant railroad equipment.","narrative":"Built in 1930 as a 4-8-2 Mountain-type steam locomotive, No. 6755 belonged to the Pennsylvania Railroad's Class M1 family, which was designed to haul both freight and passenger trains. The first M1 engines appeared in 1923, and the class run ended with 100 locomotives, the last of them from 1930. Its drivers measure 72 inches in diameter, and its boiler operated at 250 pounds of steam pressure. In 1946 a number of Class M1a locomotives, including this type, were upgraded and reclassified as M1b, adding a twenty-pound increase in steam pressure. The class proved most valuable on freight, and in its final years these engines were assigned increasingly heavy tonnage while diesels took the faster runs. No. 6755 is the only surviving example of its class, and it is listed as part of a group of rolling stock that documents Pennsylvania Railroad equipment.","period_of_significance":"1930","architect_builder":null,"architectural_style":null,"criteria":["A","C"],"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 17:11:33.469769-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/01000519.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/01000519/3e49f465b9-800.webp","url_1600":"https://nationalhistoricalregister.com/media/01000519/3e49f465b9-1600.webp","licence":"CC0","author":"Smallbones","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:RRMOP_6755.JPG\" rel=\"noopener\">Smallbones</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:RRMOP_6755.JPG"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71993185","wikipedia":"https://en.wikipedia.org/wiki/Pennsylvania_Railroad_6755","wikidata":"https://www.wikidata.org/wiki/Q16898805"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/lancaster-county/locomotive-no-6755-01000519/"}