USS South Dakota (BB-57) was the lead vessel of the four South Dakota-class fast battleships built for the United States Navy in the 1930s. The first American battleships designed after the Washington treaty system began to break down in the mid-1930s, the South Dakotas were able to take advantage of a treaty clause that allowed them to increase the main battery to 16-inch (406 mm) guns. However, congressional refusal to authorize larger battleships kept their displacement close to the Washington limit of 35,000 long tons (36,000 t). A requirement to be armored against the same caliber of guns as they carried, combined with the displacement restriction, resulted in cramped ships. Overcrowding was exacerbated by wartime modifications that considerably strengthened their anti-aircraft batteries and significantly increased their crews. wiki