The Philadelphia Naval Shipyard was the first United States Navy shipyard and was historically important for nearly two centuries.

Construction of the original Philadelphia Naval Shipyard began during the American Revolution in 1776 at Front and Federal Streets in what is now the Pennsport section of Philadelphia. In 1871, it was replaced by a new, much larger yard developed around facilities on League Island, at the confluence of the Delaware and Schuylkill rivers. The Navy Yard expansion stimulated the development over time of residences and businesses in South Philadelphia, where many shipyard workers lived. During World War II, some 40,000 workers operated on shifts around the clock to produce and repair ships at the yard for the war effort.

The U.S. Navy ended most of its activities at the shipyard in the 1990s, closing the base after recommendations by the Base Realignment and Closure commission. In 2000, the Philadelphia Industrial Development Corporation, on behalf of the City of Philadelphia, acquired it and began to redevelop the land. First called Philadelphia Naval Business Center, it is now known as The Navy Yard. It is a large mixed-use campus where nearly 15,000 people are employed by more than 120 companies representing a mix of industries, including cell therapy production facilities, global fashion companies, and a commercial shipyard. The U.S. Navy still operates a Naval Inactive Ship Maintenance Facility and a few engineering activities at the site.

The yard has its origins in a commercial shipyard founded in 1776 on Philadelphia's Front Street on the Delaware River; it was designated an official United States Navy site in 1801.

From 1812 until 1865, it was a large ship production center. The first ship launched to the water was the USS Franklin. This event was watched by more than 50,000 spectators. The rapid development of other shipbuilding companies pledged Philadelphia to improve production processes. This was the first shipyard in the world to use floating dry docks in the building process to improve an operating time of the ships.

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.

Beginning in the early 19th century, many Philadelphia workers agitated for a reduction in the arduous twelve-hour workday. Prior to 1835, the workday in the Philadelphia Navy Yard was sunrise to sunset, with time off for breakfast. In the summer of 1835 Philadelphia Navy Yard shipwrights, joiners and other workers led the effort to reduce the workday by combining the direct action of a strike, with political pressure to the executive branch. After first seeking workday reduction by a request to the Secretary of the Navy via shipyard Commandant Commodore James Barron, on 29 August 1835 they appealed directly to President Andrew Jackson. Commodore Barron endorsed his workers' request with the following acknowledgment "I would respectfully observe – Seems to be inevitable, sooner or later, for as the working man are seconded by all the Master workmen, city councils etc. there is no probability they will secede from their demands."

Their petition was granted and on 31 August 1835 the president ordered the Secretary of the Navy to grant the ten-hour work day, effective 3 September 1835. However, the change was applicable only to the Philadelphia Navy Yard. On 29 August 1836, a committee of Philadelphia Navy Yard mechanics appealed to President Andrew Jackson to extend the law,