Union Iron Works

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Union Iron Works in 1918, at Pier 70

Union Iron Works, located in San Francisco, California, on the southeast waterfront, was a central business within the large industrial zone of Potrero Point, for four decades at the end of the nineteenth and beginning of the twentieth centuries.[1]


Peter Donohue, an Irish immigrant, founded Union Brass & Iron Works in the south of Market area of San Francisco in 1849. It was later run by his son, James Donohue. After years as the premiere producer of mining, railroad, agricultural and locomotive[2] machinery in California, Union Iron Works, led by I. M. Scott, entered the ship building business and relocated to Potrero Point where its shipyards still exist, making the site on the north side of the Potrero the longest running privately owned shipyard in the United States. After Bethlehem Shipbuilding Corporation bought the works in 1905, the consolidated company came to include the Alameda Works Shipyard, located across the San Francisco Bay in Alameda and the Hunter's Point shipyard to the south.

USS Oregon in 1896 at a Bremerton, Washington state Drydock

In 1885, the Union Iron Works launched the first steel-hulled ship on the west coast, Arago, built with steel from the Pacific Rolling Mills. In 1886, UIW was awarded a $1,000,000 contract to build the cruiser USS Charleston for the United States Navy, which they completed in eighteen months. From the completion of Arago in 1884 to 1902, UIW built seventy-five marine vessels, including two of the most famous vessels of the Spanish–American War, USS Olympia and USS Oregon.[3][4]

An 1892 description of the yards stated that between 1200 and 1500 men were employed and the yearly gross revenue was between $2,000,000 and $4,000,000. By the turn of the century, the shipyard had expanded in area and employment had more than doubled to 3,500.[5] These industrial facilities used five types of power, distributed throughout; electricity, compressed air, steam, hydraulic and coal or gas fire. Union Iron works built a number of ships for the United States Navy. These ships include USS Oregon laid down in 1891, and Adder-class submarines Grampus and Pike which were launched in 1902 and 1903, respectively. The latter two were subcontracted from the Holland Torpedo Boat Company, and were the first submarines built on the West Coast.[6]

In 1902, the Union Iron Works was absorbed into a combine called the United States Shipbuilding Company and was mired in three years of litigation. In 1905, the entire 40-acre (160,000 m2) shipyard was purchased by Bethlehem Shipbuilding Corporation for one million dollars. Charles M. Schwab stood on the steps of the UIW office building on 20th Street during the auction. At this point, he was the only bidder. Schwab was widely believed to have engineered the demise of the U.S. Shipbuilding Corporation in order to gain control of the industry. Whether or not that was true, he certainly benefited from the collapse of the US Shipbuilding combine.[3]

Columbia rolled over at the company dry dock following the earthquake.

At the time of the 1906 San Francisco earthquake, the coastal passenger liner Columbia of the San Francisco and Portland Steamship Company had been undergoing a refit at the yard's hydraulic drydock. The earthquake caused the iron-hulled Columbia to shift off her supports and roll onto the drydock on her starboard side. This damaged the drydock, a key feature of the yard, beyond economic repair. Columbia on the other hand, despite being partially flooded and damaged, was repaired and returned to service in January 1907.[7][8] In 1908, Bethlehem Shipbuilding Corporation bought the Hunter's Point drydocks. In the pre-World War I era, Union Iron Works built several navy ships that became internationally famous due to the Spanish–American War including Commodore Dewey's flagship the Olympia. After 1905, the shipyard operated as part of Bethlehem Steel, and produced both warships and merchant ships. The shipyard was expanded in 1911 by purchasing Risdon Iron Works, the land next to the shipyard. Risdon Iron Works built locomotives, this was closed and a new shipyard was built to build US Navy includeing destroyers and submarines. Risdon Iron Works was founded by John Risdon of Saline, Michigan in 1896. Risdon Iron Works started by building boilers, iron pipes, steam engines and gas engines. From 1873 to 1909 Risdon Iron Works also built ships, tugs, ferries and barges. John Risdon held the patents for the first river mining dredge.[9][10] During the World War II, the yard built: C1-B cargo ships, Atlanta-class cruisers, Benson-class destroyers, Buckley-class destroyer escorts, Allen M. Sumner-class destroyers, YG and YCV Barges and Fletcher-class destroyers.[3][11]

Bethlehem shipbuilding offices 1913

World War II Slipways[edit]

Slipway Width Length Date
1 60 feet (18 m)[12] 450 feet (140 m)[12] 1885-1915[13]
2 60 feet (18 m)[12] 450 feet (140 m)[12] 1890s-1915[13]
3 60 feet (18 m)[12] 450 feet (140 m)[12] 1890s-1915[13]
4 99 feet (30 m)[14] 550 feet (170 m)[15][14] 1890s-1941[15]
5 100 feet (30 m)[16] 400 feet (120 m)[17] 1941[17]
6 100 feet (30 m)[16] 660 feet (200 m)[17] 1941[17]
7 100 feet (30 m)[16] 660 feet (200 m)[17] 1941[17]
8 100 feet (30 m)[16] 400 feet (120 m)[17] 1941[17]

Locomotives built[edit]

The named locomotives built by Union Iron Works were:[2]

Ships built[edit]

Some of the ships and ferries built by Union Iron Works include:

Ships reconstructed by the Union Iron Works include:

See also[edit]


  1. ^ "Union Iron Works Powerhouse (U.S. National Park Service)". www.nps.gov.
  2. ^ a b Kneiss, Gilbert H. (November 1946). "Locomotives of The Union Iron Works". Railway and Locomotive Historical Society Bulletin. 68: 40–49. JSTOR 43517446.
  3. ^ a b c "Bethlehem San Francisco, Union Iron Works".
  4. ^ Sacramento Daily Union, Volume 96, Number 115, 14 December 1898
  5. ^ Edison Manufacturing Co. (January 22, 1898). "Union Iron Works shipyard in San Francisco, California". loc.gov. Retrieved 19 March 2018.
  6. ^ "Pier 70: History". www.pier70sf.org.
  7. ^ "Pier 70: History". Pier 70 San Francisco - Historic Shipyard at Potrero Point (pier70sf.org). Retrieved 21 August 2013.
  8. ^ a b Belyk, Robert C. Great Shipwrecks of the Pacific Coast. New York: Wiley, 2001. Print.ISBN 0-471-38420-8
  9. ^ "Risdon Iron Works - History | VintageMachinery.org". vintagemachinery.org.
  10. ^ "Santa Cruz Water Works" – via DPLA.
  11. ^ "Union Iron Works" – via www.youtube.com.
  12. ^ a b c d e f "National Defense Migration: Washington, D. C., hearings, March 24-26, 1941. pt.12. San Diego, June 12-13, 1941". p. 4469.
  13. ^ a b c "Union Iron Works Historic District National Register Nomination March 2014" (PDF). pp. 66–67.
  14. ^ a b "Report on Survey of U.S. Shipbuilding and Repair Facilities, 1978". p. 62.
  15. ^ a b "Union Iron Works Historic District National Register Nomination March 2014" (PDF). p. 63.
  16. ^ a b c d Based upon measurements made with Google Earth of slipway remains.
  17. ^ a b c d e f g h "Union Iron Works Historic District National Register Nomination March 2014" (PDF). pp. 71–72.
  18. ^ "US Navy Ships Listed by Hull Number, CL/CA -- Light Cruisers and Heavy Cruisers". Department of the Navy, Naval History and Heritage Command. Retrieved 24 September 2020.
  19. ^ "Buckley-class destroyer escorts in World War II". Archived from the original on April 2, 2015. Retrieved March 18, 2015.
  • Bethlehem Steel Company Shipbuilding Division. A century of progress, 1849-1949: San Francisco Yard. San Francisco, 1949

Coordinates: 37°45′38.68″N 122°23′4.01″W / 37.7607444°N 122.3844472°W / 37.7607444; -122.3844472

  • Mains'l Haul - Journal of Pacific Maritime History - Fall 1998

External links[edit]