After the conclusion of the repatriation effort, "Montana" was transferred to the west coast of the United States. She arrived in the Puget Sound Navy Yard in Seattle on 16 August, where she remained until 2 February 1921, when she was decommissioned. During this period of inactivity, she was renamed "Missoula" on 7 June 1920 so her original name could be used for one of the planned "South Dakota"-class battleships, and she reclassified with the hull number CA-13. Though decommissioned in 1921, the ship remained in the Navy's inventory until 15 July 1930, when she was formally stricken from the naval register, according to the terms of the London Naval Treaty, which placed aggregate tonnage limits on the cruiser fleets of the signatory countries. She was sold to John Irwin Jr. on 29 September and was eventually broken up in 1935.