Portsmouth Naval Shipyard
U.S. Navy (NAVSEA), Kittery, Maine
Portsmouth Naval Shipyard on Seavey Island in Kittery, Maine dates to 1800 and is described as the first U.S. government navy yard. It launched 134 submarines between 1917 and 1969, including the first government-built nuclear submarine, and hosted the signing of the 1905 Treaty of Portsmouth. Today it overhauls and modernizes Navy submarines.
- Company
- U.S. Navy (NAVSEA)
- Status
- Operating
- Opened
- 1800
- Employees
- 6,500
- reference
- Industry
- Aerospace and defense
- Revised
- November 12, 2026
What is made here
Overhauls, repairs and modernizes U.S. Navy submarines; historically built warships and 134 submarines.
Facts
| Founding | The Navy Department bought Dennett's Island in 1800 for what the nomination calls the first navy yard established by the U.S. government; the yard reached its present size with the purchase of Seavey Island in 1866 (federal: npgallery.nps.gov) |
|---|---|
| Submarines | Built the first government submarine, L-8, launched in 1917, and the first government-built nuclear submarine, Swordfish (1958); 134 submarines were launched between 1917 and 1969 (federal: npgallery.nps.gov) |
| Treaty of Portsmouth | The 1905 treaty ending the Russo-Japanese War was signed in the yard's Administration Building (Building 48) (federal: npgallery.nps.gov) |
| Mission today | Mostly overhaul, repair and modernization of submarines, with more than 6,500 federal employees as of November 2021 (reference: en.wikipedia.org) |
Figures are as stated by the source named next to each one. Company figures are the company's own claims.
Can you visit?
We haven't found a public tour of this factory. See factory tours in Maine.
Sources
- NPS National Register nomination: Portsmouth Naval Shipyard (federal, checked November 12, 2026)
- Wikipedia: Portsmouth Naval Shipyard (reference, checked November 12, 2026)
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