Philadelphia is the case where the Navy actually left, and something else took its place. The Philadelphia Naval Shipyard traced back to 1801, employed 40,000 people and built 53 ships during WWII at its peak -- and BRAC recommended it for closure in 1991, citing foreign competition and the post-Cold-War drawdown.^[1] It closed for good in 1995, 7,000 jobs gone.^[1] What survived wasn't the Navy yard -- it was a separate commercial operation, built on part of the same site starting in the late 1990s, delivering its first ship in 2003.^[2] That yard exists at all because of the Jones Act, the 1920 law requiring that ships moving cargo between US ports be built, owned, and crewed domestically -- without it there's no US customer forced to buy a domestically built product tanker or container ship instead of a cheaper foreign one.^[2] The mechanism here isn't military necessity. It's protectionism, plain and legislated. And even that hasn't been enough to keep it American-owned: in 2024, South Korea's Hanwha Group bought the yard outright for $100 million.^[2] The law still requires the ships be built in Philadelphia. It says nothing about who owns the company doing the building.

Newport News is the opposite case: no law protects it, because nothing else can do what it does. Founded in 1886 as the Chesapeake Dry Dock and Construction Co., the yard delivered its first ship, a tugboat, in 1891.^[3] Today it is the sole designer, builder, and refueler of every US Navy aircraft carrier, and one of only two companies in the country that builds submarines. It built the USS Enterprise in 1960, the world's first nuclear-powered carrier, and is under contract right now for the USS Enterprise (CVN-80), a second ship carrying that name, part of the Gerald R. Ford class.^[3] Across more than 550 acres and 800-plus ships built, Newport News doesn't need a trade law.^[3] There is nowhere else to send the contract. That's a different kind of protection than Philadelphia's -- not a rule that favors it, but a capability gap nobody else has closed.

San Diego is simpler, and starker: it's what's left after everyone else on an entire coastline stopped. NASSCO traces to 1905 as California Iron Works, took its current name in 1949, and General Dynamics bought it in 1998 for $415 million.^[4] It builds oil tankers, LNG-powered container ships, and Navy auxiliary vessels -- it built the Exxon Valdez in 1986^[4] -- but the fact that actually defines it is blunter than any of that: NASSCO is the only new-construction shipyard remaining on the entire West Coast of the United States.^[4] Not the largest, not the most prestigious. The last one standing on 1,300 miles of coastline, by attrition, not by design.

Bath, Maine is the one case where the survival mechanism was chosen on purpose, and paid for on purpose. Bath Iron Works was founded in 1884 by a Civil War veteran, became a General Dynamics subsidiary in 1995, and at its WWII peak launched a destroyer every 17 days.^[5] Today it builds Arleigh Burke-class destroyers -- and it has never been the only company that can. Since the Navy awarded the first Arleigh Burke contract to Bath in April 1985, it has deliberately split every subsequent order between Bath and Ingalls Shipbuilding in Mississippi, building the identical ship class at two separate yards, on two separate coasts, continuously, for four decades. That's not inefficiency. It's insurance: if a hurricane, a labor stoppage, or a bankruptcy ever took one yard offline, the Navy still has a second one that already knows how to build the exact same ship. Bath is now the fourth-largest employer in the state of Maine,^[5] and the town's entire economic identity runs through a shipyard the Navy keeps duplicated specifically so no single point of failure -- including Bath itself -- can stop a destroyer from getting built.

Every one of these yards is, underneath the contracts and the ownership history, a steel-forming operation. A destroyer hull, a carrier's flight deck, a commercial tanker -- all of it is welded steel plate, the same material the government has spent over two decades trying to keep domestically produced, first through tariffs that lost at the WTO and then through tariffs and a board veto that haven't. A shipyard with no domestic steel supply isn't a shipyard, it's a very large empty building -- which is part of why the same industrial-policy fights over steel keep resurfacing in Navy budget debates, even though nobody in those debates is talking about ships.

Why does this matter? Line these four up against each other and "the US still builds ships" turns out to be four unrelated facts wearing one sentence. A 105-year-old cargo-trade law keeps Philadelphia's yard open, even now under foreign ownership. A capability gap nobody has closed keeps Newport News as the only carrier builder in the country. Simple attrition left NASSCO as the last yard on the whole West Coast. And in Bath, the Navy pays a premium, on purpose, to keep a second yard alive it doesn't strictly need day to day -- exactly so it isn't caught needing one it no longer has. It's the same question as the civilian auto industry's military lineage: what does it actually take to keep a specific, hard-to-rebuild industrial capability alive in a country that mostly rewards whoever builds it cheapest. The answer isn't one policy. It's whichever mechanism happened to fit that yard, in that place, at the moment it would otherwise have closed.