Trenton initially developed as a center of iron and steel production as a result of the efforts of Peter Cooper, the well-known inventor, industrialist and philanthropist from New York City. In the mid-1840s, as Cooper began to turn his attention to the large-scale manufacture of wrought and cast iron, he saw Trenton as a key element in an emerging industrial complex that ultimately sprawled across the Middle Atlantic region and beyond. Iron ore mined around Andover in the New Jersey Highlands and the hills of Eastern Pennsylvania was semi-processed into pig iron in the furnaces at Phillipsburg. The material was then shipped by canal and rail to Trenton, along with coal for fuel, where two vast ironworks hammered, rolled and drew out finished manufactured items, like rails and structural beams, as well as plates, rod and wire for use by other metalworking businesses.
In 1844-45, Peter Cooper set up his first ironworks in Trenton on the banks of the Delaware River at the foot of South Warren Street. Cooper was assisted by his son, Edward and son-in-law, Abram S. Hewitt in this endeavor which represented the first building block in the Cooper & Hewitt industrial empire. By 1854, the South Warren Street ironworks was producing 35,000 tons of finished iron annually, but capacity expanded enormously over the next century. Under a succession of owners - the South Trenton Iron Company, the Trenton Iron Company, the New Jersey Steel & Iron Company, the American Bridge Company and U.S. Steel - this plant mass-produced the first high quality iron and steel rails for the American railroads, the first structural I-beams for building construction, artillery carriages and gun-metal for the Union Army in the Civil War, the first steel made in the United State by the open hearth process, and countless materials for bridges and buildings all across the country and overseas.
Just across town, alongside the Delaware and Raritan Canal and Camden and Amboy Rail Line, the Trenton Iron Company and their agents, the Cooper & Hewitt partnership, began in 1849-50 to construct a second ironworks site. This plant was developed more specifically as a wire mill that could supply, among other clients, the growing needs of the neighboring wire rope manufacturing and engineering business of John A. Roebling. By 1853, the factory was advertising their production of telegraph wire, bridge wire, wire fencing, rivets and spikes, all made from Andover ore. The Trenton Iron Company continued production at this wire mill until 1904 when its operations were acquired by U.S. Steel.
Links to learn more - Ringwood Manor, Ringwood State Park; Invention Factory, Trenton