{"nrhp_refnum":"88000838","name":"Gerloff Road Bridge Crossing Swamp Creek","other_names":[],"category":"structure","location":{"address":"Gerloff Rd. over Swamp Creek","address_restricted":false,"city":"Lower Frederick Township","county":"Montgomery County","state":"PA","lat":40.28625599500003,"lon":-75.54371156899998,"geom_source":"nps_gis"},"listed_date":"1988-06-22","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Engineering"],"significance_levels":["state"],"summary":{"what_it_is":"A three-span stone arch highway bridge carrying Gerloff Road over Swamp Creek in Upper Frederick Township, Montgomery County, Pennsylvania. A plaque on the bridge gives its construction date as 1854.","why_significant":"The nomination describes it as a good example of a multiple-span nineteenth-century stone highway bridge. Its three segmental arches are set off from the body of the bridge by a recessed arch section, a feature said to appear to be peculiar to Montgomery County. The bridge is nominated as part of a group of stone bridges illustrating the continuing tradition of stone masonry bridge construction in Pennsylvania, and its significance is under the area of engineering.","narrative":"A three-span stone arch highway bridge crosses Swamp Creek in Upper Frederick Township, Montgomery County, Pennsylvania. Each of its three segmental arches spans 20 feet, and long approach walls extend the structure to about 125 feet overall. A plaque on the bridge gives its construction date as 1854, though the nomination notes this date is marked with a question mark in the survey. The arch spans are set apart from the body of the bridge by a small built-in recession, which outlines a rectangle across both arch crowns. The nomination states that this detail appears to be peculiar to Montgomery County, where five stone arch bridges share it. The bridge is significant in engineering as a representative example of nineteenth-century stone masonry bridge construction in Pennsylvania. It was listed as part of a group of ten stone bridges in Montgomery County, built between 1789 and 1910. The south parapet, wingwalls and one pier have been reconstructed.","period_of_significance":null,"architect_builder":null,"architectural_style":"Segmental stone arch bridge","criteria":["C"],"status_note":"South parapet, wingwalls and pier reconstructed; use is vehicular.","vacant_flag":null,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:36.51503-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/88000838.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/88000838/f18150bd9c-800.webp","url_1600":"https://nationalhistoricalregister.com/media/88000838/f18150bd9c-1600.webp","licence":"Public domain","author":"PennDOT","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Bridge_in_Upper_Frederick_Township,_Gerloff_Road.jpg\" rel=\"noopener\">PennDOT</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Bridge_in_Upper_Frederick_Township,_Gerloff_Road.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71993388","wikipedia":"https://en.wikipedia.org/wiki/Gerloff_Road_Bridge_Crossing_Swamp_Creek","wikidata":"https://www.wikidata.org/wiki/Q4966381"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/montgomery-county/gerloff-road-bridge-crossing-swamp-creek-88000838/"}