Answer: 1917

During World War II, the largest single shipyard in the world with more than 35,000 people was located in Chester, Pennsylvania. Sun Shipbuilding and Dry Dock Company opened in 1916 during World War I. At this time, ships were scarce as many were sent overseas for wartime use. In response to this, the Sun Oil Company also known as “Sunoco,” built the Sun Shipbuilding and Dry Dock Company along the Delaware River. Its first ship, the Chester Sun, was launched in late 1917. 

Sun Shipbuilding was a very productive yard that pumped out hundreds of ships, primarily tankers and cargo ships, during its existence. The company built for Sun Oil, private parties, other oil companies, and, particularly during World War II, the U.S. Maritime Commission. The yard built more than 250 tankers for the war and repaired more than 1,500 ships that were damaged during the conflict. It developed many new building technologies and became known for its use of "All-Welded Construction."

In the early 1980s the yard was sold and renamed Pennsylvania Shipbuilding Company. It closed in late 20th century and was eventually handed over to the state. Now the site is the home of Harrah’s Philadelphia Casino and Racetrack and a Kimberly-Clark production plant.

Images of Sun Ship and its workers can be found in HSP's Philadelphia Record morgue photograph collection (#V07).  Additionally, we also have many resources in the history of shipbuilding in Philadelphia and other shipyards, including the Navy Yard and Cramp's Shipyard.

Image: “Change of shifts at Sun Shipyard,” photograph (5 August1946).