{"nrhp_refnum":"84000903","name":"Alexander-Acacia Bridge","other_names":["Alexander Avenue Overhead","Bridge No. 27C-150"],"category":"structure","location":{"address":"Alexander Ave. between Acacia and Monte Vista Aves.","address_restricted":false,"city":"Larkspur","county":"Marin County","state":"CA","lat":37.93013468200007,"lon":-122.53182614399998,"geom_source":"nps_gis"},"listed_date":"1984-01-05","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Community Planning and Development","Engineering","Architecture"],"significance_levels":["local"],"summary":{"what_it_is":"A reinforced concrete through-arch road bridge carrying Alexander Avenue over the now-abandoned Northwestern Pacific Railroad right of way in Larkspur, Marin County, California. It was built between 1925 and 1927 to a design by engineer John C. Oglesby.","why_significant":"The nomination argues the bridge represents a type (reinforced concrete through arch), a period (1920s) and a method of construction (poured-in-place reinforced concrete). It is one of only five such bridges known in California. It also played an important, if controversial, role in developing the Palm Hill Tract by linking it to older Larkspur.","narrative":"Alexander-Acacia Bridge carries Alexander Avenue across the former Northwestern Pacific Railroad right of way in Larkspur, California. Built between 1925 and 1927, it measures 163.5 feet long and 29 feet wide. Seven reinforced concrete slab spans make up the structure, and the main span is a through arch holding the deck on suspended pillars and transverse floor beams. Engineer John C. Oglesby is named as its designer, and Pacific States Construction Company won the contract with a bid of $49,927.32. The bridge replaced a lighter wooden crossing and connected older Larkspur with the new Palm Hill Tract. Property owners in the improvement district were assessed the cost, which prompted protests from residents, a bank and the railroad, all of which were denied. It is one of only five reinforced concrete through-arch bridges known in California, all from the mid to late 1920s. Today it still serves as the main vehicle route into the Palm Hill Tract.","period_of_significance":"1925-1927","architect_builder":"Engineer: John C. Oglesby; built by Pacific States Construction Company of San Francisco","architectural_style":null,"criteria":[],"status_note":"Still in its original function, providing the Palm Hill Tract with its primary vehicular access to downtown Larkspur. Condition is marked fair and the site is occupied/in use.","vacant_flag":false,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:54:27.334464-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_CA/84000903.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/84000903/df3728dcdd-800.webp","url_1600":"https://nationalhistoricalregister.com/media/84000903/df3728dcdd-1600.webp","licence":"CC BY-SA 4.0","author":"Marthature","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Alexander_Avenue_Bridge_-_View_from_Below.jpg\" rel=\"noopener\">Marthature</a>, <a href=\"https://creativecommons.org/licenses/by-sa/4.0\" rel=\"license noopener\">CC BY-SA 4.0</a>, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Alexander_Avenue_Bridge_-_View_from_Below.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/123859652","wikipedia":"https://en.wikipedia.org/wiki/Alexander-Acacia_Bridge","wikidata":"https://www.wikidata.org/wiki/Q111843050"},"indexable":true,"url":"https://nationalhistoricalregister.com/california/marin-county/alexander-acacia-bridge-84000903/"}