A turret shell for the cancelled USS Massachusetts
USS Massachusetts BB-54 was a South Dakota class battleship laid down in 1920 for the U.S. Navy, but never completed.
The South Dakotas were authorized in 1917, but work was postponed so that the U.S. Navy could incorporate information gained from the Battle of Jutland, fought in mid-1916, in their design. Work was further postponed to give destroyers and other small fighting vessels priority as they were needed urgently to fight German U-boats in the North Atlantic. Construction started only in 1920. As the Washington Naval Treaty of 1922 both restricted the total battleship tonnage allowed the U.S. Navy, and limited individual ship size to 35,000 long tons (36,000 t), construction was halted in early 1922. The unfinished hull was scrapped the following year when Massachusetts was 11.0% complete. The guns were transferred to the U.S. Army and their boilers and armour were used to modernize older battleships.