{"nrhp_refnum":"89000819","name":"Station KPH Operating Station","other_names":["Marconi Property"],"category":"building","location":{"address":"18500 CA 1","address_restricted":false,"city":"Marshall","county":"Marin County","state":"CA","lat":38.14407097600008,"lon":-122.87842704299999,"geom_source":"nps_gis"},"listed_date":"1989-07-24","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Communications"],"significance_levels":["national"],"summary":{"what_it_is":"A one-and-a-half-story steel frame and concrete operating building with a red tile hipped roof, built in 1913 on the east shore of Tomales Bay near Marshall, Marin County, California. It was part of the Marconi wireless receiving station later known as Station KPH.","why_significant":"The nomination argues national significance in communications because Station KPH made trans-Pacific radio communication possible. With its Bolinas transmitting counterpart, it linked California with Hawaii and, through Hawaii, with Japan, and it provided ship-to-shore service across the Pacific. The Operating Building housed the receiving equipment and the staff who ran it.","narrative":"This concrete and steel-frame building on a hill above Tomales Bay, near Marshall in Marin County, was built in 1913 as the operating building of the Marconi wireless receiving station later known as KPH. It measures about 84 by 41 feet and has a red tile hipped roof, a basement with thick concrete walls, and plain, utilitarian design. It originally held eight rooms for receiving equipment and staff offices, plus an open veranda on the bay side. The station, built by the J.G. White Engineering Company and dedicated in September 1914, worked with a transmitting station at Bolinas to connect California with Hawaii and, through Hawaii, Japan. It also handled ship-to-shore traffic over the Pacific. The Navy took it over in 1917, and the Radio Corporation of America ran it from 1920 until radio operations moved in 1931. The site was chosen because it was barren and free of vegetation that could interfere with reception. Later uses include residential use, and the veranda has since been enclosed.","period_of_significance":"1914-1931","architect_builder":"J. C. White Engineering Company (the text also calls it the J.G. White Engineering Company of New York City)","architectural_style":null,"criteria":["A"],"status_note":"Used as a residence for the property's General Manager; the form says the property is being rehabilitated as a non-profit conference center. The veranda has been enclosed and interior walls reconfigured.","vacant_flag":false,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:54:28.174562-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_CA/89000819.pdf"},"photo":null,"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/123859715","wikipedia":"https://en.wikipedia.org/wiki/KPH_(radio_station)","wikidata":"https://www.wikidata.org/wiki/Q14594560"},"indexable":true,"url":"https://nationalhistoricalregister.com/california/marin-county/station-kph-operating-station-89000819/"}