Conceived and built during the desperate days of World War II, the carriers of the Midway class carried a crew of 4,500 and up to 70 aircraft. The 1,000 foot-long Midway was once the largest carrier afloat, growing from 45,000 tons in 1945 to 74,000 tons in 1991. However, she had a displacement about two-thirds that of contemporary nuclear-powered flattops. When operating at sea the ship was refueled every three days, burning approximately 100,000 gallons of oil a day. When first built, the Midway's bow was open to the sea, and was enclosed in 1957 as part of a major overhaul.