San Juan, CL-54, was an Atlanta-class antiaircraft cruiser, named for the city in Puerto Rico. Bethlehem Steel at Fore River, Quincy, laid her down on 15 May 1940, launched her on 6 September 1941, Mrs. Margarita Coll de Santori sponsoring, and commissioned her on 28 February 1942, Captain James E. Maher in command.
She left Hampton Roads on 5 June 1942 in the Wasp group, gave gunfire support at Tulagi on 7 August, and was patrolling off the transport area on the night of 8 and 9 August during the Battle of Savo Island. She escorted the damaged Enterprise to Pearl Harbor after the Eastern Solomons, raided the Gilberts on 16 October and sank two patrol vessels. At Santa Cruz on 26 October 1942, during the last dive-bombing attack, one bomb passed through her stern, flooded several compartments and damaged but did not disable her rudder.
In 1943 she covered the New Georgia and Bougainville operations, joined the raids on Rabaul, and on 4 and 5 December fought off persistent torpedo plane attacks during the Essex raid on Kwajalein. After an overhaul at Mare Island she covered the Eniwetok occupation in February 1944. She escorted carriers at Palau, Hollandia, Truk and the Marianas, was in the Battle of the Philippine Sea, and screened carriers at Formosa, Luzon and in the South China Sea from December 1944 to January 1945. In 1945 she escorted Hornet against Tokyo and Okinawa, and DANFS records that planes from her group helped sink the battleship Yamato on 7 April.
She joined the fleet entering Sagami Wan on 27 August 1945. Her embarked unit commander, Commodore Rodger W. Simpson, was responsible for freeing and evacuating Allied prisoners of war in Japan, and on 29 August she entered Tokyo Bay and landed parties that freed prisoners at Omori, Ofuna and the Shinagawa hospital. She was decommissioned on 9 November 1946 and struck on 1 March 1959. NavSource gives the sale for scrap as 31 October 1961 to National Metals and Steel at Terminal Island. She earned 13 battle stars.