During World War II, the Basalt Rock Company located south of the City of Napa on the Napa River, built 3 dozen salvage rescue tugs for the United States Navy. Following the war, several small and medium size businesses began operating in the County. A large majority of these businesses were related to the wine industry and tourism. Agriculture in the county remained very diverse until late in the 20th century when wine grapes again became the primary focus. While vineyards were planted on well over 90% of the agricultural land in the county, by the end of the 20th century, modern day farmers have recently begun exploring the possibility of raising other food crops in order to again diversify and take advantage of growing conditions.