The second USS San Juan (CL-54), and the first to be named for the city of San Juan, Puerto Rico, was an Atlanta-class light cruiser of the United States Navy. She was laid down on 15 May 1940 by the Bethlehem Steel Co., Quincy, Massachusetts; launched on 6 September 1941; sponsored by Mrs. Margarita Coll de Santori; and commissioned on 28 February 1942.

The Atlanta-class cruisers were eight United States Navy light cruisers which were designed as fast scout cruisers or flotilla leaders but which proved to be effective anti-aircraft cruisers during World War II. They were also known as the Atlanta-Oakland class. The Atlanta class originally had 16 x 5-inch (127 mm)/38 caliber guns in eight two-gun turrets, arranged with three superfiring turrets forward, three more superfiring aft and two waist mounts, one port and one starboard, giving the first four Atlanta-class cruisers the heaviest anti-aircraft armament of any cruiser of World War II. The last four ships of the class, starting with Oakland, had a slightly revised armament with a reduced main gun battery - the waist turrets being deleted - as they were further optimized for anti-aircraft fire in light of war experience.