Arizona saw the lions share of the casualties during the Pearl Harbor attack. Of the 2,403 Americans killed during the attack, 1,177 were Arizona sailors. The ship had 1,512 men aboard that morning, so these was almost a 78% fatality rate.

That in and of itself doesn’t explain why the ship has become so symbolic of the attack, but it is a major factor. The focus of memorials is often centered on the largest body count.

The salvage operations after Pearl Harbor were also a major factor. If Arizona had suffered the same number of dead, but been easier to salvage, this would be a completely different discussion.

The initial focus was on salvaging ships and components that could quickly be returned to service in some form. The 900 page Pearl Harbor Salvage Diary details many of the daily operations on these ships, but to summarize the lightly and moderately damaged ships were first priority, typically being made ready for sea and sent to the West Coast for full repairs. These were mostly back in action by May 1942. The sunken battleships, the target ship Utah, and the minelayer Oglala were slowly prepared for salvaging, pumping out oil, sending divers to seal off compartments to pump dry, removing scrap steel and potentially reusable components (like Arizona’s two aft turrets and the guns from the second), and as time came to refloat them adding large patches to the outside of the ship. Efforts generally were focused on the ships that could return to battle quickly. However, almost every day there was some type of operation on every ship still on the bottom of Pearl Harbor, generally divers getting deeper into the ship, securing and pumping compartments dry, and/or removing certain components. For example, the aft magazines of Arizona were pumped dry and all ammunition removed, including the small arms locker, in the spring of 1942.

By August 1942, this work left three ships still on the bottom of Pearl Harbor: Arizona, Oklahoma, and the target ship Utah. These were the lowest priority ships as they had the lowest military value. Arizona was considered a complete loss from the start and was right next to her mooring piers, so was back of the line for salvage work: essentially Berth F-7 was essentially occupied but not much more. Utah was an old battleship turned into a target ship, and I have never found a reference suggesting they intended to return her to service in any form besides her late striking date. However, the ship did capsize and roll towards the channel, so while ships could still pass, they wanted to provide more margin and clear the wreck if possible. Information on Oklahoma is not as detailed (the only battleship where I don’t have any type of damage report), and it’s not clear exactly when the Navy decided she was a constructive total loss. However, she was even further into the channel than Utah, so despite taking more damage was higher on the salvage list, though it’s possible that the hope of repairing her played a contributing role.

Oklahoma was thus the priority target for salvage operations from late 1942, with an extensive parbuckling operation to right the ship so she could be refloated like the other battleships. At this same time, divers were thoroughly inspecting Arizona, finding her back was broken. This complicated the salvage operations, and is the first hint in the document trail of leaving part of the ship in place. However, as of January 1943 she was still to be salvaged. Quoting from the Salvage Diary:

January 30, 1943

Subject: USS OKLAHOMA, ARIZONA and UTAH- Status of Salvage Operations.

USS ARIZONA

Future salvage operations to refloat as large a part of this vessel as practicable, possible the entire ship, have been approved by the Vice Chief of Naval Operations under date of 15 January, and the agreement with the contractor mentioned for the UTAH will cover the ARIZONA also.

I have not found further records on when the complete salvage operations were canceled, only a couple vague references that are more inference than I like. But as of January 1943 they wanted as much of the ship removed as practical.

Note, Oklahoma was still upside down at this time. After righting the ship and refloating the hull, the teams moved to Utah, but unlike Oklahoma she began to slide along the bottom rather than continue to roll upright. They got her out of the channel and called it good, they didn’t even remove some of the now-accessible 5” guns.

At this point, you thus had two wrecks left on the bottom of Pearl Harbor: the battleship Arizona and the target ship Utah. Both had small memorials by 1951, as seen in some Navsource photographs: the 1971 Utah memorial replaced this original plaque. But Arizona became the target for the major memorial after the war for several reasons: she was still there, was the grave for hundreds of her crew rather than 79 on Utah (her CO’s Navy Cross citation commends him for “direct[ing] the abandonment of the ship when it was capsizing rapidly, in such a cool and efficient manner that approximately ninety per cent of the crew were saved”), as a battleship was more interesting than a target ship (this unfortunately plays a major role in which ships get attention from the masses, often disproportionately to their importance), and was on the side of Ford Island that faces the main base. I will let others address the postwar situation in detail, as my knowledge there is superficial.