Her keel was laid in March, 1914. She was launched in June, 1915. The period between the laying of the keel and the launch is traditionally considered the building period by maritime historians. The keel-laying is considered the birth of a ship. The period between the launch and commissioning, or acceptance by the buyer, is considered outfitting and shakedown.
Therefore, when the life of a ship is described on record, as in the case of the USS Arizona, it would read like this:
Laid Down: 16 March, 1914, as Hull No. BB-39, Brooklyn Navy Yard, NY.
Launched: 19 June, 1915, BNY, NY.
Commissioned into Service: USN as USS Arizona, 17 October 1916.
Refitted: 1929 – 1930, Norfolk Navy Yard, Norfolk, VA.
Fate: Sunk under hostile action at Ford Island, HI, 7 December 1941.
Decommissioned: 29 December, 1941.
According to tradition, anyone guessing either 1914 or 1915 would be technically correct as this was the building window.