{"nrhp_refnum":"80000820","name":"Round Valley Flour Mills","other_names":[],"category":"building","location":{"address":"Main and Greely Sts.","address_restricted":false,"city":"Covelo","county":"Mendocino County","state":"CA","lat":39.79294250200007,"lon":-123.25025100999994,"geom_source":"nps_gis"},"listed_date":"1980-11-10","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Industry","Historic - Aboriginal","Commerce","Agriculture","Architecture"],"significance_levels":["national"],"summary":{"what_it_is":"A steam-powered steel roller grain mill at the southwest corner of Main and Greely Streets in Covelo, Round Valley, Mendocino County, California. It was developed in 1888 on the site of an earlier blacksmith shop and remodeled in 1914.","why_significant":"The mill survives as a virtually unaltered example of a steam-powered, steel roller grain mill, with its original steam engine and redwood-spouted machinery intact. It served as Covelo's main grain processing center from about 1890 to 1940 and shipped flour to nearby communities. The form also notes its potential for historic archaeology and its place in local literary and social history.","narrative":"Standing at the corner of Main and Greely Streets in Covelo, this weathered wooden mill processed grain for Round Valley and beyond. John S. Rohrbough developed it in 1888 on the site of an older blacksmith shop, whose east wing still survives, including a post burned with local cattle brands. In 1914 he remodeled it, adding a three-story section, a decorative false-front facade and a steam engine room, using plans drawn up in San Francisco. Inside, the original steam engine and redwood-spouted steel roller machinery remain, giving a clear picture of how such a mill worked. Regular flour production ended in 1937, and the machinery rolled barley and wheat for hog feed until the 1960s. It ran again in 1975 to process a local harvest. The form describes it as a rare survivor, with only one comparable mill known in the state. It is also tied to local literary history through a novelist's character, Ann Mitchell.","period_of_significance":"1888-1914","architect_builder":"1914: Engineer Spaulding; Carpenter/builder Long","architectural_style":null,"criteria":[],"status_note":"Listed as vacant and unoccupied, in fair condition. Vandalism and deterioration are noted, but the mill has been virtually unchanged since the 1914 remodeling.","vacant_flag":true,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:55:32.108067-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_CA/80000820.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/80000820/a797d675af-800.webp","url_1600":"https://nationalhistoricalregister.com/media/80000820/a797d675af-1600.webp","licence":"CC BY-SA 3.0","author":"NoeHill","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Round_Valley_Flour_Mill.jpg\" rel=\"noopener\">NoeHill</a>, <a href=\"https://creativecommons.org/licenses/by-sa/3.0\" rel=\"license noopener\">CC BY-SA 3.0</a>, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Round_Valley_Flour_Mill.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/123859820","wikipedia":null,"wikidata":"https://www.wikidata.org/wiki/Q133305591"},"indexable":true,"url":"https://nationalhistoricalregister.com/california/mendocino-county/round-valley-flour-mills-80000820/"}