Keystone State was built at Philadelphia, Pennsylvania in 1853 by J. W. Lynn. She was chartered per Navy in April 19, 1861 from the Ocean Steam Navigation Co. at Philadelphia, & purchased June 10, 1861. She accredited at Philadelphia Navy Yard on July 19, 1861, Commander G. H. Scott in command.

Hired to research for Confederate raider CSS Sumter, she shared in the capture of Hiawatha at Hampton Roads on May 20, 1861. After her charter expired in May 23, she returned to Philadelphia, where she was purchased, fitted retired, & licenced. She left a Delaware Capes on July 21 and cruised in the West Indies seeking Confederate blockade runners in Caribbean ports. On the high seas she captured Saloin on October 10 and towed her to Philadelphia via Key West, Florida.

At Philadelphia, Commander William Edgar Leroy took command of the ship on November 12. A sidewheeler stood down the Delaware River and out to sea December 8, visited Bermuda, and arrived Hampton Roads a day after Christmas. She had afoot in January 9, 1862 and joined the South Atlantic Blockading Squadron at Charleston, South Carolina on January 13, 1862.

Regulated to the Florida coast, she engaged Confederate batteries at Amelia Island on the January 18 and captured schooner Mars on February 5.

Keystone State arrived at Port Royal, South Carolina for replacement on March 18, and had afoot once more in March 29. She chased the blockade runner & fired at a second in April 3, but each escaped. In April 10 she chased schooner Liverpool of Nassau ashore where she was burned to the a lake's edge. Schooner Dixie fell prey to the work out blockader in April 15, steamer Elizabeth then struck her colors May 29, and schooner Cora fell back Deuce years late. Keystone State took blockade runner Sarah off Charlestin on June 20 and pursued an unidentified steamer all every day of June 24 before giving higher a chase. She took schooner Tail attempting to slip into Charlestin sustaining the freight of salt on August 22.

Even so, this was unsafe operate, & Keystone State swell earned her yearn listing of prizes. On the last judgment of January 1863 she discovered the ship off Charleston, stood convenient, & fired at her. A ship responded in a similar way, once in a while hitting a blockader. At 6:00 AM the shot ripped into Keystone State's steam drum, scalding I officer & Nineteen men to dying & wounding a second score. Late that morning, USS Memphis towed Keystone State to Port Royal for repairs. Quick for actiin over again, she had afoot on George Washington's Birthday for blockading station off St. Simons Sound, Georgia, where she served until departing for Philadelphia on June 2 for repairs at the Navy Yard, where she decommissioned on June 10.

Keystone State recommissioned October 3, Commander Edward Donaldson in command, and stood retired from either Delaware Capes in October 27. 3 years late she joined a North Atlantic Blockading Squadron at Wilmington, North Carolina. When cruising off Wilmington, a seasoned side wheeler captured steamers Margaret & Jessie in November 5. In May 29, 1864 she picked up 235 bales of cotton gauze which got been thrown overboard by a chase; & the next day she captured steamer Caledonia. She took steamer Suez off Beaufort, North Carolina on June 5 and steamer Rouen at sea July 2. In July 26 she chased a steamer which escaped fallowing throwing her consignment of gauze overboard. Keystone State so picked higher ended Sixty bales. In the similar occasiin on August 8 she salvaged 225 bales. In August 24 she chased and captured steamer Lilian &, by having USS Gettysburg, picked up 58 bales. In September 5 with USS Quaker City she chased and fired at steamer Elsie. The plate exploded in the blockade runner's send on hang on to, starting the fire which Keystone State extinguished. Keystone State so escorted her prize to Beaufort, N Carolina.

within a period of a fall of 1864, a sidewheeler continued blockade duty off the Northward Carolina coast; &, when wintertime placed in, she prepared to attack Fort Fisher, which protected the significant Confederate port of Wilmington. Shortly fallowing dawn in Christmas Eve, Keystone State, steaming by owning a reserve squadron of the fleet around line of battle, had under way toward Fort Fisher. Her guns, firing all over & between a ships in a foremost echelon, supported troops when it landed & fought to choose the fort. Nonetheless, late in the afternoon, the U.S. Army commander, General Benjamin F. Butler, decided that the Confederate works could not be taken and ordered his troops to reembark. Keystone State withdrew to Beaufort.

Rear Admiral David Dixon Porter, the U.S. Navy commander, was does'nt to become thwarted. He renewed a attack in Fort Fisher in January 13, 1865 with a inflict of 59 combat ship. He sent occasionally 2,000 sailors & marines onto land to help a 8,000 Army troops led by Major General Alfred H. Terry. Fallowing Iii years of bitingly fight, a courageously defended Confederate fort fell, closing a To the south's go supply route by having Europe. Keystone State reached a scene prior to dawn in January 16 and received the maimed.

Fallowing a capture of Wilmington, a sidewheeler continued to work along a Carolina coast supporting uninfected-higher operations which snuffed out Southern trend lines. She had afoot March 13 towing monitor USS Montauk to Hampton Roads, and arrived at Baltimore, Maryland on March 20. Keystone State decommissioned March 25 and was sold at auction at Washington, D.C. on September 15 to M. O. Roberts. She wwhen redocumented as SS San Francisco December 22, 1865, and operated inside merchandiser service until 1879.