In 1914, the Panama Canal opened, allowing the easy movement of U.S. Navy ships between the Atlantic and Pacific oceans. In June 1919, President Wilson transferred half of the U.S. Navy, about 200 ships, to the Pacific Coast.
An Associated Press story in the June 17, 1919, Los Angeles Times explained:
WASHINGTON, June 16––Orders making effective the proposed division of the United States naval forces into two fleets of equal strength, one to be called the Atlantic, and the other the Pacific Fleet, were issued tonight by the Navy Department.
Each of the two fleets will be comprised of four divisions of battleships and dreadnoughts, two divisions of cruisers, eighteen divisions of destroyers, three divisions of submarines and two divisions of mine layers.
Supply, repair, fuel and hospital ships, tugs and other auxiliaries will be equally divided between the two fleets. As the Pacific fleet heretofore has consisted of only a few battleships and some armored and light cruisers and destroyers, docking facilities and naval bases on the Pacific Coast probably will have to be greatly enlarged. …
On Aug. 9, 1919, the Pacific Battle Fleet anchored in the Port of Los Angeles at San Pedro. The port featured local availability of fuel oil – saving money – and good weather allowing frequent gunnery exercises.
The battle fleet would stay until May 1940. A United Press wire story in the May 8, 1940, Los Angeles Times announced:
HONOLULU, May 7, (U.P.) The United States Battle Fleet today unexpectedly was ordered to remain indefinitely in Hawaiian water and carry out further tactical exercises and maneuvers instead of returning to California bases.
The order, announced by Admiral James O. Richardson, commander-in-chief of the Fleet, means the main body of the American Fleet will be concentrated at this mid-ocean Gibraltar of the Pacific until its duties are completed…
Remaining here indefinitely will be 11 battleships, 14 cruisers, three aircraft carriers, more than 40 destroyers, 16 auxiliary and base ships and 23 submarines from mainland bases, plus the Hawaiian detachment of 10 heavy cruisers and 20 destroyers. Added to these is the large auxiliary naval air force.
Forty-two thousand five hundred officers and men will remain with these ships in the Hawaiian area. …
Of note: in May 1941, the battleships Mississippi, Idaho and New Mexico were among a group of ships transferred to the Atlantic Fleet – thus missing the Dec. 7, 1941, attack on Pearl Harbor by the Japanese navy.