Intended for the newly established American Line, the four ships—Pennsylvania, Ohio, Indiana and Illinois—were at the time the largest iron ships yet built in the United States,[2][3] and were launched with considerable fanfare.

Although soon outclassed by newer and larger vessels, all four of the Pennsylvania class steamships were to enjoy long and distinguished careers, the last of them being retired from service in 1921.

The Railroad made its first attempt to compensate for the lost traffic by organizing its own steamship line in 1863 (during the American Civil War), but the plan was dropped after the Philadelphia city council declined to provide financial support.

The winning bidder was Cramp & Sons, which submitted the lowest bid of $520,000 per unit, and the contract for all four ships was subsequently signed with that company on August 30.

[3] The company began by purchasing real estate at Norris St., Philadelphia, a few blocks from its existing works, on which it built an entirely new shipyard, which was fitted with its own blacksmith, engine, boiler and carpentry shops in addition to a 700-foot outfitting wharf.

Many parts for the ships however, such as iron plates, anchor chains, joinery for the first class cabins, gas fixtures etc., came from specialist Philadelphian manufacturers under subcontract.

Cramp had expanded his company's workforce to over 1,000 to build the ships, but strong industry-wide demand at the time made it difficult to find skilled workers.

The event was considered of such patriotic and economic significance that a half day holiday was declared for the cities of Philadelphia and Camden and the surrounding area.

On December 28, Philadelphia's Mayor William S. Stokley presented the American Line with four twelve pound Dahlgren howitzers intended for installation on the ships as signal guns—a gesture of civic pride in the achievement of building the four vessels.

[14] When completed, each of the four Pennsylvania class ships was fitted with a 2,000 horsepower compound steam engine serviced by several large boilers, delivering power to a single propeller.

Each vessel had a single large stack amidships and two schooner-rigged auxiliary masts, one fore and one aft, capable of utilizing a total of ten sails.

In the course of its ten-year history, the ASC had cost the PRR almost a million dollars, although the losses were offset to some extent by the extra business the Pennsylvania class ships had brought to the railroad.

[24] The main difference between the ASC and the INC was that the former had run American-built, American-flagged ships, while the latter employed foreign built vessels which sailed under the Belgian flag and operated under the name of the Red Star Line.

[25] Between 1887 and 1891, all four ships of the class were refitted with smaller but more modern triple expansion steam engines, which were more economical to run and allowed for more cargo space.