the late 1950s through the early 1970s. Since that time, only Electric Boat and Newport News have built submarines for the US Navy. World War II During World War II, the company built 74 submarines, while Elco built nearly 400 PT boats, and Electric Boat ranked 77th among United States corporations in the value of World War II military production contracts. Post war In 1952, Electric Boat was reorganized as General Dynamics Corporation under John Jay Hopkins. General Dynamics acquired Convair the following year, and the holding company assumed the "General Dynamics" name while the submarine-building operation reverted to the "Electric Boat" name. Electric Boat built the first nuclear submarine which was launched in January 1954, and the first ballistic missile submarine in 1959. Submarines of the , , , and es were also constructed by Electric Boat. In 2002, EB conducted preservation work on Nautilus, preparing her for her berth at the US Navy Submarine Force Library and Museum in Groton, Connecticut where she now resides as a museum. Electric Boat's first submarine Holland was scrapped in 1932. From the mid-1970s to the present, EB has been one of only two submarine manufacturers in the United States with the other being Newport News Shipbuilding in Virginia. Electric Boat overhauls and undertakes repair work on fast attack class boats. The company built the Ohio-class ballistic missile submarines and Seawolf-class submarines, as well as others. In April 2014, EB was awarded a $17.8 billion contract with Naval Sea Systems Command for ten Block IV Virginia-class attack submarines. It is the largest single shipbuilding contract in the service's history. The company builds the submarine along with Huntington Ingalls Industries Newport News Shipbuilding. The boats of Block IV Virginias will cost less than Block III, as Electric Boat reduced the cost of the submarines by increasing efficiency in the construction process. The submarines of this type will build on the improvements to allow the boats to spend less time in the yard. In 2019 EB received a contract with Naval Sea Systems command to begin procuring materials for the Block V variant of the Virginia-Class. This upgrade brings the Virginia payload module, which enables Tomahawk missiles to be carried by the submarine. 1980s structural welding defect cover up In the early 1980s, structural welding defects had been covered up by falsified inspection records, and this led to significant delays and expenses in the