Portsmouth Naval Shipyard

Portsmouth Naval Shipyard is a United States Navy installation on Seavey’s Island in the Piscataqua River at Kittery, Maine, opposite Portsmouth, New Hampshire. Established on June 12, 1800, during the administration of President John Adams, it is the oldest continuously operating shipyard in the U.S. Navy’s public-yard system. Its location was selected because the river provided access to the Atlantic and was less vulnerable to seasonal ice, while the surrounding region supplied timber and an experienced shipbuilding workforce. The yard began as a conventional naval construction and repair facility. During the nineteenth century it built wooden sailing warships, steam vessels, gunboats, frigates, sloops, tugs, and other naval craft. It also repaired important vessels, including USS Constitution in 1855. The installation expanded with shiphouses, barracks, a hospital, marine facilities, and other infrastructure. Its association with the 1905 Treaty of Portsmouth, which ended the Russo-Japanese War, gave the yard an important place in diplomatic as well as naval history. Portsmouth entered submarine construction during World War I, producing L-8 and later boats of several diesel-electric classes. Its role expanded dramatically during World War II, when the yard built more than 70 submarines and employed nearly 25,000 civilian workers at its wartime peak. After the war, the facility became an important center for submarine design, development, construction, and maintenance. USS Albacore, launched in 1953, introduced a highly influential teardrop hull form that shaped modern submarine design. USS Swordfish, launched in 1957, was the first nuclear-powered submarine built at the yard, and USS Sand Lance, launched in 1969, was the last submarine constructed there. Since the end of new-submarine construction, Portsmouth Naval Shipyard has concentrated on complex maintenance and industrial support. Its principal work includes submarine overhauls, depot-level repairs, nuclear refueling, modernization, testing, and life-cycle support. The yard is particularly associated with Los Angeles-class and Virginia-class submarine work, although specific assignments vary over time. Major infrastructure programs have included dry-dock improvements, crane-rail upgrades, waterfront support facilities, pumping systems, communications renovations, and construction of expanded capacity for Virginia-class submarine maintenance. The shipyard has repeatedly faced questions about its future. A proposed closure in the 1960s was ultimately abandoned, and a 2005 Base Realignment and Closure recommendation was reversed after employees, elected officials, unions, and regional supporters organized the Save Our Shipyard campaign. The facility remains a major federal workplace and regional economic institution. In November 2021 it employed more than 6,500 federal personnel, supplemented by private contractors working on specialized engineering and industrial tasks. Its historic motto, “From Sails to Atoms,” reflects the transition from wooden sailing ships to nuclear-powered submarine support.

The Piscataqua River region had a substantial shipbuilding tradition before the naval yard was created. Colonial and revolutionary-era vessels were built on nearby islands, including Raleigh and Ranger, while Congress, one of the first six frigates authorized for the United States Navy, was constructed in the region between 1795 and 1799. In the 1790s, Navy Secretary Benjamin Stoddert selected the site for the first federally established U.S. Navy shipyard. The government acquired Fernald’s Island, later incorporated into Seavey’s Island, and strengthened harbor defenses by rebuilding the former Fort William and Mary as Fort Constitution. The shipyard was formally established on June 12, 1800. Commodore Isaac Hull became its first naval commander, serving initially from 1800 to 1802 and returning during the War of 1812. The yard’s first major vessel was Washington, a 74-gun ship of the line launched in 1814 under the supervision of master shipbuilder William Badger. During the nineteenth century, Portsmouth developed into a broad naval industrial complex. Barracks were added in 1820, marine facilities in 1827, and a hospital in 1834. The Franklin Shiphouse, completed in 1838 and later enlarged, became one of the country’s largest structures of its type before being destroyed by fire in 1936. The yard built and repaired wooden warships, steam vessels, gunboats, sloops, frigates, and support craft. Among its notable repair assignments was the 1855 overhaul of USS Constitution. The installation also served military and diplomatic functions. Prisoners captured during the Spanish-American War were held there in 1898. Construction of the Portsmouth Naval Prison began in 1905; its castle-like main structure led to the nickname “The Castle.” The prison operated until 1974 and also housed captured German submarine personnel during the world wars. In 1905, the General Stores Building hosted the Treaty of Portsmouth negotiations, through which representatives of Russia and Japan concluded the Russo-Japanese War. President Theodore Roosevelt received the 1906 Nobel Peace Prize for his role in arranging the settlement. Portsmouth began building submarines during World War I, with L-8 recognized as the first submarine constructed by a U.S. Navy yard. Production expanded during World War II, when the yard built more than 70 submarines and its civilian workforce approached 25,000. After 1945, Portsmouth shifted toward submarine design, development, overhaul, and support. The launch of Albacore in 1953 marked a major technical milestone: its teardrop-shaped hull and circular cross-section influenced submarine hydrodynamics internationally. The yard subsequently launched Swordfish, its first nuclear-powered submarine, in 1957. Sand Lance, launched in 1969, was the final submarine built at Portsmouth. The yard’s survival was not always assured. In 1965, a Department of Defense plan proposed closing Portsmouth among a large group of military installations. The facility received an extension, and the closure plan was rescinded in 1971. A later Base Realignment and Closure recommendation in 2005 again threatened the yard. Employees and regional supporters formed the Save Our Shipyard campaign, lobbying against closure. On August 24, 2005, the installation was removed from the closure list. The yard received a Meritorious Unit Commendation for work performed from 2001 to 2004, including early completion of submarine availabilities and substantial safety improvements. In the modern period, Portsmouth has focused on nuclear-submarine maintenance rather than new construction. Its work includes overhaul, repair, refueling, modernization, testing, and related industrial services. Infrastructure investments have included upgrades to communications facilities, dry docks, cranes, pumping systems, waterfront support buildings, and Virginia-class submarine capacity. The shipyard has also accommodated other federal maritime and military activities, including Coast Guard use of the harbor and the relocation of the U.S. Army New England Recruiting Battalion in 2010. Environmental management became another significant part of the yard’s history. In 1994, the Environmental Protection Agency placed the installation on the National Priorities List under the Superfund program after investigations identified PCBs, petroleum-related compounds, metals, benzene, and other contaminants in soil, sediment, and groundwater. Following approximately three decades of remediation, the EPA removed the shipyard from the list in 2024. A separate boundary dispute with New Hampshire reached the Supreme Court, which dismissed the case in 2001; New Hampshire nevertheless renewed its sovereignty assertion through a 2006 legislative resolution. Portsmouth continues to operate as one of the four remaining public shipyards directly operated by the U.S. Navy.

1. 2024Removed from Superfund list

   The EPA removed the shipyard from the National Priorities List after extensive remediation.

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2. 2005Removed from proposed BRAC closure list

   The Save Our Shipyard campaign helped secure removal of the installation from the 2005 closure recommendation.

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3. 1994Added to Superfund National Priorities List

   The EPA listed the shipyard for investigation and remediation of environmental contamination.

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4. 1971Closure plan rescinded

   A proposed closure associated with a 1960s defense-base review was ultimately abandoned.

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5. 1969Last submarine built at the yard launched

   USS Sand Lance was launched as the final submarine constructed at Portsmouth.

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6. 1957First nuclear-powered submarine launched

   USS Swordfish became the first nuclear-powered submarine launched at Portsmouth.

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7. 1953Albacore launched

   USS Albacore introduced a teardrop hull and circular cross-section that influenced later submarine design.

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8. 1917Submarine construction begins

   L-8 became the first submarine built by a U.S. Navy yard at Portsmouth.

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9. 1905Treaty of Portsmouth hosted

   The yard hosted negotiations that ended the Russo-Japanese War.

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10. 1838Franklin Shiphouse completed

    A large shiphouse was completed and later extended to accommodate construction of Franklin.

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11. 1814Washington launched

    The 74-gun ship of the line Washington became the first major vessel launched by the newly established yard.

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12. 1800Shipyard formally established

    The United States established the Portsmouth Naval Shipyard on June 12, creating the first formally established federal Navy shipyard at the site.

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Highly specialized U.S. Navy public shipyard focused on complex submarine maintenance, refueling, modernization, and industrial support.

• Submarine overhaul and repairNaval maintenance

  Portsmouth performs major depot-level availabilities for submarines, involving inspection, structural work, mechanical and electrical repair, systems testing, and return-to-service preparation. The work is substantially more extensive than routine fleet maintenance and can require long-duration dry-dock access and coordination across government and private industrial teams.

• Nuclear submarine refuelingNuclear naval maintenance

  The yard supports nuclear-powered submarine refueling and associated overhaul activities. These projects combine reactor-related work with modernization, safety inspections, equipment replacement, testing, and broader maintenance required to extend the operational life of a submarine.

• Submarine modernizationNaval modernization

  Modernization work updates submarine combat, navigation, communications, habitability, propulsion-support, and other systems during scheduled maintenance periods. The exact scope depends on the class, configuration, mission requirements, and Navy program schedule.

• Historic submarine constructionNaval shipbuilding1917

  Although Portsmouth no longer specializes in new submarine construction, its historical production included World War I submarines, extensive World War II diesel-electric submarine classes, and nuclear-powered vessels such as USS Swordfish. USS Sand Lance was the last submarine launched by the yard in 1969.

• 2005Save Our Shipyard

  United States

  Employees and regional supporters organized a public and political campaign opposing the 2005 Base Realignment and Closure recommendation that would have closed Portsmouth Naval Shipyard. The campaign emphasized the yard’s submarine expertise, workforce, national-security role, and regional economic importance.

  Outcome. The shipyard was removed from the closure list on August 24, 2005, and continued operating.

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• 2021Expanding Virginia-class submarine support capacityGeneration change

  The growing Virginia-class submarine fleet required additional maintenance infrastructure and specialized waterfront support.

  What changed. The Navy advanced Dry Dock 2 construction, began a Virginia-class waterfront support facility, installed high-capacity dewatering pumps, and awarded a contract for a new Virginia-class maintenance dry dock.

  Aftermath. The investment positioned Portsmouth to support future Virginia-class overhaul and modernization workloads.

  Contract value for Virginia-class submarine maintenance dry dock. $1.73 billion (2021)

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• 2020Modernizing dry docks and waterfront infrastructureOther

  Aging facilities and expanding submarine maintenance requirements created demand for upgraded dry docks, cranes, communications systems, and waterfront support assets.

  What changed. Navy contracts addressed communications-building renovations, Dry Dock 1 flood-basin and crane-rail work, Dry Dock 2 crane upgrades, Building 2 renovation, and other waterfront projects.

  Aftermath. The projects strengthened the yard’s capacity for complex submarine maintenance.

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• 2005Retaining Portsmouth during BRAC reviewStrategy

  The 2005 Base Realignment and Closure process recommended the shipyard for closure, creating a major institutional and regional challenge.

  What changed. The Navy and regional stakeholders supported the Save Our Shipyard campaign and presented operational, workforce, and national-security arguments for retention.

  Aftermath. The installation was removed from the closure list and continued as an active public Navy shipyard.

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• 1965Responding to a proposed shipyard closureStrategy

  A Department of Defense review proposed closing Portsmouth as part of a wider plan affecting numerous military bases.

  What changed. The Navy granted the facility a ten-year extension, and the closure order was later rescinded in 1971.

  Aftermath. Portsmouth remained in operation and continued its transition toward specialized submarine work.

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• 2024Portsmouth Naval Shipyard removed from EPA Superfund National Priorities List

  The Environmental Protection Agency removed the 278-acre shipyard from the National Priorities List after decades of investigation and remediation addressing contaminated soil, sediment, and groundwater.

  RegulationOther
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• 2021Virginia-class submarine dry-dock project receives $1.73 billion contract

  A major Navy contract supported construction of additional dry-dock capacity intended to maintain and modernize Virginia-class submarines at the shipyard.

  OtherProduct generation
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• 2021Portsmouth Naval Shipyard expands Virginia-class waterfront support infrastructure

  Construction activity included a Virginia-class submarine waterfront support facility, Dry Dock 2 work, and installation of high-capacity dewatering pumps for Dry Dock 1.

  Other
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• 2005Portsmouth Naval Shipyard receives Meritorious Unit Commendation

  The commendation recognized performance between September 2001 and August 2004, including early completion of major submarine availabilities, improved safety, and progress against operational and financial targets.

  Other
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• 2005CDC and NIOSH publish study of leukemia mortality among shipyard workers

  A study examined deaths among employees between 1952 and 1992 and reported an association between cumulative occupational ionizing-radiation dose and leukemia mortality risk.

  OtherRegulation
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• 2001U.S. Supreme Court dismisses New Hampshire boundary claim

  The Court dismissed New Hampshire’s case concerning sovereignty over Seavey’s Island and the shipyard, leaving the installation in Maine.

  Lawsuit
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1. Portsmouth Naval Shipyard
2. Portsmouth Naval Shipyard — Naval Sea Systems Command