Between the late 1880s and 1890s, the government awarded the yard $43,000 for the construction of a new, larger, and more up-to-date hospital. In June 1900, Congress gave permission for a stone dry dock to be built at the shipyard. The new dock, costing $1,089,000 was a 750-foot long granite structure.
Portsmouth soon emerged as the new submarine-building yard for the Navy. This saved the government millions because it no longer had to go through expensive private contractors. At the yard’s peak during WWI, it employed 5,722 people, including approximately 1,000 women. During the war, 122 vessels were repaired at Portsmouth Naval Shipyard.
Delivering sixty-seven more submarines during WWII, Portsmouth showed no signs of abandoning its specialty. The shipyard went through a name change from the Portsmouth Navy Yard to the Portsmouth Naval Shipyard in September of 1945. At this time, the yard employed a record 20,466 people. Eventually, Portsmouth would incorporate new technologies to build the experimental submarine called the Albacore (AGSS-569). This new submarine had a groundbreaking “tear-drop” shaped hull and became the model for the hydrodynamic hull design later used in all submarines.
This new construction work fell off in the early 1970s and the company began to focus exclusively on submarine repair work. Later, the company was found to be polluting the Piscataqua River with toxic run-off and is estimated to cost approximately $406.8 million to have it cleaned up.