Lighthouses of California · Sources & Method

Companion to the interactive map. Last updated 2026-09-14. Every station on the map carries its own citations in its popup; this page explains what the map is built on, how its positions were fixed, and where the primary record contradicts the familiar story.

1. The primary layer: the Light-House Board's own reports

This map's backbone is 163 passages quoted verbatim from the annual reports of the United States Light-House Board and its successors, cited per passage to report year and printed page. Through the 1870s the Board's report was printed inside the Annual Report of the Secretary of the Treasury on the State of the Finances; later it appeared as its own volume, and after 1903 within the reports of the Department of Commerce and Labor and then as the Annual Report of the Commissioner of Lighthouses. The complete run for fiscal years 1852 through 1876 was read for this project, along with volumes reaching to 1919. Passages appear in the popups as marked quotations, never paraphrased into the surrounding prose.

Gaps, stated plainly: sixteen year-volumes between 1876 and 1900 could not be obtained, nor those for 1901–1903 or 1923. Where a station's date rests on a secondary work quoting the Board rather than on the Board's text read directly, the popup's "Source grade for the date" row says so.

2. What the Board's record corrects

• Alcatraz and the "first lighthouse on the Pacific coast." No statement calling Alcatraz first appears in the Board's reports. Its own printed Light List of 1858 (pp. 482–483, under "When built") gives both Alcatraz and Point Pinos as 1854, with every other California station 1855 or later, and does not rank them. What the Board does say, in 1857 (p. 229), is the baseline:

  "There were no lights or other aids to navigation at that time in the harbors or bays on the Pacific coast of the United States."

  ; "that time" being October 1852, when it took charge. The map therefore attributes the "first" claim to the standard accounts rather than to the Board.
• Mare Island's fog bell was not new. The 1874 report (p. 682) records:

  "The fog-bell and machinery formerly in use at Point Bonita light-station has been removed to this station, where a suitable house has been built for it."

  Accounts giving Cape Mendocino as its source are mistaken.
• The Board contradicted itself about where Mare Island's tower stood; "the southern end" in its 1872 order, the "extreme eastern end" in its 1874 list. The Coast Pilot settles it: the station was established on the extreme southeastern part of the island.

3. Coordinates

Positions come from published sources wherever one exists: the current U.S. Coast Guard Light List (with its LLNR numbers) for stations still charted, and nineteenth-century Coast and Geodetic Survey positions printed in the Pacific Coast Pilot for stations long gone. Two stations this project first treated as unlocatable; Mare Island and the 1856 Humboldt Harbor light; turned out to have published C&GS positions in the 1889 Coast Pilot (pp. 240 and 325); both were read from the volume's own text before being adopted, and both superseded earlier estimates, one of which had been about 1.4 km wrong. Where no published position exists, the pin is marked as an area estimate and the popup states the derivation and its expected error:

• Carquinez Strait (original station); derived from the Notice to Mariners of January 1910, which placed it about 9/16 mile on a true bearing of 106° 30′ from the Mare Island light; ±400 m, plus ±140 m because the notice does not say whether its miles are statute or nautical.
• Oakland Harbor; position not established. No published latitude and longitude for the 1890 or 1903 structure was found; the pin marks the harbour approach the station served and should be read with about 1.5 km of uncertainty.

4. Scope

Every maritime aid with a station of its own: manned light stations, fog-signal stations, the minor beacons of San Francisco Bay, and the two lightship stations; the San Francisco bar and Blunts Reef; where no tower could be built. Layers are eras of establishment; filters cut by type, present condition, and region.

5. Photographs

47 of 48 stations carry a historic photograph. The great majority are United States government works in the public domain: National Archives Record Group 26 (the Lighthouse Service's own photographs), U.S. Coast Guard Historian's Office images, and Historic American Buildings Survey work at the Library of Congress. Each carries its credit, collection, and negative number where known. Every image URL was verified before publication, and every subject checked against its catalog record; an image whose record does not actually name the station is not used.

6. Principal sources

Primary

• Annual Report of the Light-House Board, fiscal years 1852–1910 (printed in the Annual Report of the Secretary of the Treasury through the 1870s; thereafter separately and within the Department of Commerce and Labor reports).
• Annual Report of the Commissioner of Lighthouses, 1911 onward.
• U.S. Coast Guard, Light List, Volume VI, Pacific Coast and Pacific Islands (2025), for present positions and characteristics.
• George Davidson, Pacific Coast. Coast Pilot of California, Oregon, and Washington, 4th ed. (GPO, 1889), for nineteenth-century positions and station descriptions.
• Notices to Mariners, Twelfth District, as printed in the San Francisco press.

Secondary

• National Register of Historic Places nominations under the Light Stations of California multiple-property submission (NPGallery), cited by reference number per station.
• U.S. Coast Guard Historian's Office, historic light-station information and photography, California.
• U.S. Lighthouse Society, Lighthouse Research Catalog.
• Ralph Shanks and Lisa Woo Shanks, Guardians of the Golden Gate and Lighthouses and Lifeboats of the Redwood Coast.

7. Verification

Before publication every assertion on this map; about 310 of them; was audited against its sources by an independent adversarial pass, and 23 corrections were applied: coordinates moved to published positions, superlatives attributed or softened, dates reconciled with the Board passages quoted in the same popup, and one National Register listing that had been recorded as absent restored with its reference number. Separately, the whole of the map's prose was scanned against the full text of the Board's reports and the Coast Pilots for unquoted borrowing; what the scan caught was corrected, and quoted material carries quotation marks and a citation. Errors that survive are mine; corrections are welcome by way of the site's errata page.