R-20 (Submarine No. 97) was laid down 4 June 1917 by the Union Iron Works, San Francisco, Calif.; launched 21 January 1918; sponsored by Mrs. Arnold Foster; and commissioned 26 October 1918, Lt. Comdr. Alfred E. Montgomery in command.
Fitted out at San Pedro, R-20 remained off southern California operating between San Pedro and San Diego, until March 1919. She then moved to San Francisco; underwent overhaul, and on 17 June got underway for Hawaii. She arrived at Pearl Harbor 25 June.
Designated SS-97 in July 1920, she served with the fleet training submarine personnel and assisting in the development of submarine equipment and tactics for over a decade. On 12 December 1930, she departed Pearl Harbor and headed for Philadelphia and inactivation. She arrived at Philadelphia 9 February 1931; decommissioned 15 May; and was berthed at League Island.
R-20 recommissioned 22 January 1941. In April she shifted to New London. There she trained personnel and conducted patrols until June. She then moved south to Key West, arriving on the 22d to spend the remainder of her career as a training ship.
R-20 decommissioned at Key West 27 September 1945 and was struck from the Navy list the following month. On 13 March 1946, she was sold to Macey O. Scott, Miami, Fla.