Philadelphia’s original navy yard, begun in 1776 on Front Street and Federal Street in what is now the Pennsport section of the city, was the first naval shipyard of the United States. The new, much larger yard grew up around facilities begun in 1871 on League Island at the confluence of the Delaware and Schuylkill rivers. The shipyard’s greatest period came in World War II, when the yard employed 40,000 people who built 53 ships and repaired 574. During this period, the yard built the famed battleship New Jersey and its 45,000-ton sister ship, Wisconsin. In the Naval Laboratory, Philip Abelson developed the liquid thermal diffusion technique for separating uranium-235 for the Manhattan Project.
The City of Philadelphia became the landlord and owner of The Navy Yard in March 2000, when the Philadelphia Authority for Industrial Development (PAID) took title to roughly 1,000 acres from The Navy. The Navy Yard is home to 120 companies with 10,000 employees, as the campus continues to expand and develop. In January 2013, company announced about increasing the number of apartments for employees (near 1,000) and infrastructure development. This is made possible by the public financing of shipyards and investments of private companies. According to the plan for 2013 the number of employees at the shipyard amount to around 30,000 people.