During World War II, Evansville was a major center of industrial production which helped revive the regional economy after the Great Depression. A huge, 45-acre shipyard complex was constructed on the riverfront east of St. Joseph Avenue for the production of oceangoing LSTs (Landing Ship-Tanks). The Evansville Shipyard was the nation's largest inland producer of LSTs. The Plymouth factory was converted into a plant which turned out "bullets by the billions," and many other companies switched over to the manufacture of war material. In 1942 the city acquired a factory adjacent to the airport north of the city for the manufacture of the P-47 Thunderbolt fighter aircraft, known as the P-47Ds. Evansville produced a total 6,242 P-47s, almost half of the P-47s made nationally during the war.