Color-tinted postcard of USSPennsylvania, circa 1905–1908
Class overview
Name	Pennsylvania class
Builders	William Cramp & Sons, PA (2) Newport News Shipbuilding, VA (2) Union Iron Works, CA (2)
Operators	United States Navy
Preceded by	USS Brooklyn (ACR-3)
Succeeded by	Tennessee class
Built	1901–1908
In commission	1905–1927
Completed	6
Active	0
Lost	1
Scrapped	5
General characteristics (as built)[1]
Type	Armored cruiser
Displacement	13,680long tons (13,900 t) (standard) 15,138 long tons (15,381 t) (full load)
Length	504 ft (153.6 m)
Beam	69 ft 6 in (21.2 m)
Draft	26 ft 1 in (7.95 m)
Installed power	16 ×Babcock & Wilcox boilers (32 ×Niclausse boilers inPennsylvania andColorado) 23,000 ihp (17,000 kW) (design)
Propulsion	2 × vertical, inverted,triple-expansion engines 2 × screws
Speed	22 kn (41 km/h; 25 mph)
Complement	830
Armament	4 ×8 in (203 mm)/40caliber Mark 5 guns (2 × 2) 14 ×6 in (152 mm)/50 cal Mark 6 guns 18 ×3 in (76 mm)/50 calrapid fire (RF) guns 12 ×3-pounder (47 mm (1.9 in)) RF guns 2 ×1-pounder (37 mm (1.5 in))saluting guns 2 ×18 inch (450 mm)torpedo tubes
Armor	Belt: 6–5 in (152–127 mm) Turrets: 6.5 in (165 mm) Deck: 4 in (102 mm) slope, 1.5 in (38 mm) flat Conning Tower: 9 in (229 mm)
General characteristics (1911)[2]
Armament	4 ×8 in/45 cal Mark 6 guns (2 × 2), remainder of armament unchanged
General characteristics (1919)[3]
Armament	4 × 8 in/45 caliber Mark 6 guns (2 × 2) 4 × 6 in/50 caliber Mark 6 guns 10 × 3 in/50 caliber RF guns 2 × 3 in/50 caliberanti-aircraft guns All 3-pounder guns removed

ThePennsylvania class of sixarmored cruisers served in theUnited States Navy from 1905 to 1927. All six were renamed for cities 1912–1920, to make the state names available for the newbattleships beginning with thePennsylvania-class battleships. All of these served duringWorld War I, withCalifornia (thenSan Diego) being the only ship of the class to be lost. The remaining five armored cruisers were scrapped between 1930 and 1931 in accordance with theLondon Naval Treaty.

These ships were ordered infiscal years 1900 (ACR-4 to ACR-6) and 1901 (ACR-7 to ACR-9) as part of the naval buildup touched off by the Spanish–American War.^[4] Together with the four immediately succeedingTennessee-class ships they were called the "Big Ten".^[5] They were originally intended to operate in thebattle line with battleships. However, their role was changing even as they entered service. The 1904 report of the Navy'sBureau of Navigation, examining the results of theRusso-Japanese War, noted that "...the work of the armored cruisers was auxiliary to that of the battleships..." and "They can serve with battleships, but they can never take their place".^[5] In 1906 the US Navy's battleships were concentrated in the Atlantic, and three or four armored cruisers were assigned to theAsiatic Fleet in thePhilippines to counter Japan's rising naval power. By 1912 the rapid development ofdreadnought battleships andbattlecruisers left the armored cruisers unable to successfully engage the newer capital ships.^[5]

These ships were originally armed with four8-inch (203 mm)/40caliber Mark 5 guns in two twin turrets fore and aft.^[1][6] However, these were replaced with8-inch/45 caliber Mark 6 guns by 1911 as a result of a gun bursting onColorado in 1907.^[7] Fourteen6-inch (152 mm)/50 caliber Mark 6 guns were mounted incasemates on the sides.^[8] The large secondary armament, intended to combattorpedo boats, included eighteen3-inch (76 mm)/50 caliberrapid fire (RF) guns^[9] and twelve3-pounder (47 mm (1.9 in)) RF guns.^[10] Two1-pounder (37 mm (1.5 in))saluting guns and two 18-inch (457 mm)torpedo tubes were also carried.^[1]

In the development of these ships CaptainSigsbee, formerly of the ill-fatedMaine, successfully argued for adequate armor protection at the expense of speed.^[5] The belt armor was 6 in (152 mm) at the waterline with a 5 in (127 mm) upper belt, but was only 3.5 in (89 mm) at the ends. The turrets had up to 6.5 in (165 mm) on the faces. The protective deck had 4 in (102 mm) on the sloped sides and 1.5 in (38 mm) in the flat middle. Theconning tower was 9 in (229 mm) thick.^[1][5]

The engineering plant included 16 coal-firedBabcock & Wilcox boilers (32Niclausse boilers in the Cramp-builtPennsylvania andColorado)^[2] supplying 250 psi (1,700 kPa) steam to two inverted vertical four-cylindertriple-expansion engines, totaling 23,000 ihp (17,000 kW) for 22 kn (41 km/h; 25 mph) as designed. On trialsSouth Dakota achieved 22.24 kn (41.19 km/h; 25.59 mph) at 28,543 ihp (21,285 kW).^[5] The normal coal allowance was 900 tons, but this could be increased to 2,000 tons.^[1]

In 1909–1911 the ships' original 8-inch/40 caliber guns were replaced with four8-inch (203 mm)/45 caliber Mark 6 guns in Mark 12 turrets due to a gun bursting onColorado in 1907.^[1][6][7] From 1911 themilitary foremasts were replaced withcage masts.^[5] In 1911,Pennsylvania was fitted with an after flight deck for the first landing on a ship by an aircraft. This was a one-off demonstration on 18 January 1911 with pilotEugene Ely, who had performed the first takeoff from a ship onUSS Birmingham (CL-2) two months earlier.^[1][5] From 1915 to theAmerican entry into World War I in April 1917,Huntington and twoTennessee-class ships hadcatapults forseaplanes (which disabled the after turret) and carried up to four aircraft;Huntington could also tether anobservation balloon, which was used during convoy escort duty in the war. However, by late 1917, the aircraft program was cancelled and the catapults removed.^[5]

During the US participation inWorld War I several changes were made to these ships. All but four of the 6-inch guns were removed to armmerchant ships and reduce the potential of flooding through the lower casemates; this was a factor in the loss ofSan Diego (probably to a mine) in July 1918.^[3][5] The 3-inch single-purpose guns were reduced to ten, while two 3-inch/50 caliberanti-aircraft guns were added.^[11] However, the officialShips' Data Book series indicates that by 1921 all of the 6-inch guns were remounted, only to be dismounted again by 1929.^[5][12]

By 1919 the 32 Niclausse boilers inPittsburgh (ex-Pennsylvania) andPueblo (ex-Colorado) were replaced by 20 Babcock & Wilcox boilers.^[3] By 1921,Pueblo had 16 Babcock & Wilcox boilers, whilePittsburgh had 12 Babcock & Wilcox and eight "modified Niclausse" boilers.^[12] In 1922,Pittsburgh's forward funnel and the associated boilers were removed, leaving her with 12 Babcock & Wilcox boilers.^[1]

In 1922–1923 modernization of the eight survivors of these ships and theTennessee class was considered but not implemented. Possible upgrades would be new boilers and engines for a speed of 25–27 kn (46–50 km/h; 29–31 mph), a more seaworthy bow, protection improvements, and new triple8-inch/55 caliber gun turrets as in thePensacola class.^[5]

ThePennsylvanias spent the years prior to 1917 patrolling Latin America and the Western Pacific.Colorado landed troops in a 1912intervention in Nicaragua. Early in the US participation in World War I the ships operated in the South Atlantic and the Pacific, then most were transferred toconvoy escort duty in the North Atlantic.Pittsburgh remained in the Pacific, unsuccessfully patrolling for Germancommerce raiders. While usingHuntington'sobservation balloon on convoy escort duty on 17 September 1917, the balloon landed in the water due to rough weather, with the basket upside down and submerged.Shipfitter First ClassPatrick McGunigal received theMedal of Honor for rescuing the pilot.^[13] This is said to be the first action in World War I that resulted in the award of the Medal of Honor.San Diego was sunk on 19 July 1918, probably by amine laid byU-156 offFire Island, New York.^[1] The wreck remains in place. Most of the ships were decommissioned or relegated to virtually stationary roles such as "receiving ship" in the early 1920s; however,Pittsburgh andHuron continued to operate for most or all of that decade. All were sold for scrap in 1930–1931 in compliance with the limits of theLondon Naval Treaty.Huron survived as a floating breakwater inPowell River, British Columbia until wrecked by a storm in 1961. Her wreck remains in place.^[14]

The six ships of thePennsylvania class were:^[4]

ThePennsylvania class was renamed 1912–1920 to free their names for newbattleships; they were given the designationCA (armored cruiser) on 17 July 1920 with the USN's adoption of the hull-number system^[4]

• Tennessee-classcruiser – extensive discussion of US armored cruiser development and comparisons with foreign designs
• List of cruisers of the United States Navy

•  This article incorporates text from thepublic domainDictionary of American Naval Fighting Ships.

• Bauer, K. Jack; Roberts, Stephen S. (1991).Register of Ships of the U.S. Navy, 1775–1990: Major Combatants.Westport, Connecticut: Greenwood Press.ISBN 0-313-26202-0.
• Friedman, Norman (1984).U.S. Cruisers: An Illustrated Design History.Annapolis, Maryland: Naval Institute Press.ISBN 0-87021-718-6.
• Gardiner, Robert; Chesneau, Roger (1979).Conway's All the World's Fighting Ships 1860–1905. New York: Mayflower Books.ISBN 0-8317-0302-4.

Wikimedia Commons has media related toPennsylvania class cruiser.

• Pennsylvania-Class armored cruisers (Archive from 16 September 2008)
• hazegray.org: US Cruisers List: Armored Cruisers (Pre-1920 ACR Series)
• Cruiser photo gallery index at NavSource Naval History

• Cruiser classes
• Pennsylvania-class cruisers
• World War I cruisers of the United States

• Articles with short description
• Short description is different from Wikidata
• Wikipedia articles incorporating text from the Dictionary of American Naval Fighting Ships
• Commons category link is on Wikidata