Philadelphia Naval Shipyard The Navy Yard , formerly known as the Philadelphia Naval Shipyard and Philadelphia Naval Business Center , was an important naval shipyard of the United States for over a century . It is now a large industrial park that includes a commercial shipyard , Aker Philadelphia Shipyard . Philadelphia ' s original navy yard , begun in 1776 on Front Street in what is now the Center City district , 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 United States Navy ended most of its activities there in the 1990s , and in 2000 , the city of Philadelphia took over and began to redevelop the land . Today , the navy maintains a Reserve fleet and a few engineering activities at the site . History . Naval use . The yard has its origins in a shipyard on Philadelphia ' s Front Street on the Delaware River that was founded in 1776 and became an official United States Navy site in 1801 . After the advent of ironclad warships made the site obsolete , new facilities were built in 1871 on League Island at the confluence of the Delaware and Schuylkill Rivers . The Naval Aircraft Factory was established at the League Island site in 1917 . Just after World War I , a 350 - ton capacity hammerhead crane was ordered for the yard . Manufactured in 1919 by the McMyler - Interstate Company in Bedford , Ohio , the crane was called the League Island Crane by its builder . Weighing 3 , 500 tons , the crane was shipped to the yard in sections , and it was the world ' s largest crane at the time . The " League Island Crane " was for many years the Navy ' s largest crane . Its 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 U - 235 for the Manhattan Project . After the war , the workforce dropped to 12 , 000 , and in the 1960s , new ships began to be contracted out to private companies . The yard built its last new ship , the command ship " Blue Ridge " , in 1970 . The yard ' s closure was originally recommended in 1991 by the Base Realignment and Closure Commission , as a result of foreign competition and reduced needs due to the end of the Cold War . The planned closing was unsuccessfully litigated to the US Supreme Court in " Dalton v . Specter " . Although local politicians tried to keep the yard open , it finally closed in 1995 with a loss of 7 , 000 jobs . Senator Arlen Specter charged that the Department of Defense did not disclose the official report on the closing . This resulted in a controversy that led to further legal disputes , to no avail . Since its transfer from the government , the west end of property has been leased to Aker Kværner , a tanker and commercial shipbuilding firm . In the 1990s , the U . S . Navy reduced its activities there , and ended most of them on September 30 , 1995 , by decision of the Base Realignment and Closure Commission ( BRAC ) . Post - naval use . 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 . Currently , the Philadelphia Industrial Development Corporation ( PIDC ) manages the planning , operation , and development of The Navy Yard on behalf of PAID and the City of Philadelphia . A comprehensive master plan was developed in 2004 to turn the former industrial yard to a vibrant , mixed - use campus . As of 2010 , navy activities there include Naval Support Activity Philadelphia , the Naval Surface Warfare Center Ship Systems Engineering Station , Naval Facilities Engineering Command Mid - Atlantic Public Works Department Pennsylvania ( NAVFAC MIDLANT PWD PA ) and the Naval Inactive Ship Maintenance Facility ( NISMF ) , which stores decommissioned and mothballed warships and auxiliary naval vessels . The Navy Yard is home to 120 companies with 10 , 000 employees , as the campus continues to expand and develop . Clothing manufacturer Urban Outfitters consolidated its Philadelphia headquarters on the site , while Tasty Baking Company , makers of Tastykake s , has moved their bakery to the 26th Street side of The Yard . Other companies there include Iroko Pharmaceuticals , Aker Philadelphia Shipyard , Rhoads Industries , Philadelphia Industrial Development Corporation ( PIDC ) , Energy Efficient Buildings Hub ( EEB Hub ) , RevZilla . com , and Mark Group , Inc . In April 2013 , pharmaceutical giant GlaxoSmithKline opened a 205 , 000 - square - foot building in The Navy Yard ' s Corporate Center . The memorial to the Four Chaplains also sits on the grounds . The Athletic Base Ball Club of Philadelphia hosts the annual Philadelphia Base Ball Fair & Exhibition on the Navy Yard Marine Parade Grounds .