{"nrhp_refnum":"14000150","name":"Union Iron Works Historic District","other_names":["Potero Works, Union Yard, Bethlehem Steel Yard","Potrero Yard, San Francisco Yard"],"category":"district","location":{"address":"E. of Illinois between 18th & 22nd Sts.","address_restricted":false,"city":"San Francisco","county":"San Francisco","state":"CA","lat":null,"lon":null,"geom_source":null},"listed_date":"2014-04-17","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Maritime History","Industry","Architecture"],"significance_levels":["national","local"],"summary":null,"photo":null,"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":null,"wikipedia":null,"wikidata":null},"indexable":false,"url":"https://nationalhistoricalregister.com/california/san-francisco/union-iron-works-historic-district-14000150/"}