St. Louis was then detached from TF 17 to resume escorting convoys between Hawaii and California, along with one to the New Hebrides. She next joined the escort for the ocean liner , which was carrying Manuel L. Quezon, the President of the Philippines, to the United States. The ships arrived in San Francisco on 8 May, and the next day, St. Louis got underway to return to Pearl Harbor. There, she joined a group of ships carrying reinforcements to Midway during the preparations for the Battle of Midway. St. Louis was used to carry two companies of the 2nd Marine Raider Battalion and a battery of guns. The ships offloaded aircraft and marines on 25 May, and St. Louis was then transferred to Task Force 8, which was sailing north to bring reinforcements to the Aleutian islands. At that time, the unit also included her sister ships and , the heavy cruisers and , and fourteen destroyers, commanded by Rear Admiral (RADM) Robert Alfred Theobald.
