Encyclopedia of Greater Philadelphia

Iron Production

Long before western Pennsylvania dominated the American iron and steel industries, southeastern Pennsylvania and southern New Jersey became the epicenter of colonial iron production. In a little over forty years beginning in 1716, Pennsylvania ironmasters erected nearly fifty furnaces and forges for producing iron stock and goods, and by 1840 the region’s national preeminence had been secured—Pennsylvania’s two hundred charcoal furnaces produced 286,000 tons of iron (half the national total), achieving a more than fivefold increase in just thirty years. The foundation for this stupendous ascent began in colonial New Jersey, the birthplace of charcoal-fueled iron production in the Middle-Atlantic region.

Industrial iron production, which originated in North America with the Hammersmith Works (est. 1643) at Saugus, Massachusetts, began in New Jersey in 1674 at the Tinton Falls Ironworks near Shrewsbury, Monmouth County. Ironworks opened in Burlington County, New Jersey, by 1715, and by 1730 Isaac Pearson (c.1685-1749) and his partners had fired the Mount Holly Ironworks—one of the oldest in southern New Jersey. In Pennsylvania, meanwhile, Berks County’s Thomas Rutter (c.1660-1730) ignited Pennsylvania’s first forge, Pool Forge, in 1716 and Colebrookdale Furnace in 1720.

A photograph of two small pieces of bog iron.

Limonite, better known as bog iron, was the basis for iron production in southern New Jersey. (Photograph by Arthur Murphy for The Encyclopedia of Greater Philadelphia)

Geographically and geologically, the counties of southern New Jersey were particularly well suited to charcoal-fueled iron production. A chemical reaction between the tannin-rich waters of the Pine Barrens and underlying iron-rich green sands and marls formed iron-rich deposits of limonite, also known as bog iron or bog ore. Bog ore could be harvested from the banks and beds of the region’s swamps and wet meadows with little effort. For fuel, colliers converted tens of thousands of acres of hardwood forests in the west and pines in the sandy east to charcoal. Coastal shell beds could be processed into lime and used as flux. In addition, southern New Jersey’s tidal creeks performed a double service by empowering bellows and massive trip hammers and floating iron from the interior to markets on the Delaware River and beyond. In Pennsylvania the forested Delaware, Schuylkill, and Susquehanna River Valleys provided ironmasters with fuel and waterpower. In contrast to southern New Jersey, where bog iron was easily harvested, Pennsylvania’s ironworkers had to mine natural deposits of magnetite, hematite, and carbonate to secure ore. In the absence of shell beds limestone deposits served as flux for their furnaces.

The earliest colonial ironworkers typically operated simple furnaces known as bloomeries or Catalan forges. In these forges bloomsmen smelted (extracted) workable iron directly from base iron ore or from molten “pig” iron produced by the furnace. While some ironmasters anticipated shipping their iron stock to Britain, most sold to local craftsmen who produced wrought-iron nails, tools, hardware, wheel rims, and horseshoes for domestic markets, or directly to local merchants and consumers as cast-iron hollow ware and stoves.  

A black and white photograph of the manor house at the Batsto iron plantation, in its late ninenteenth century Italianate form.

The owner of the Batsto iron plantation, along with the workers, lived on the plantation. When Joseph Wharton, a Philadelphia businessman, bought Batsto in 1876 he renovated the former home of the plantation owner into the Italianate style pictured here. (Library of Congress)

Early ironworks in southern New Jersey and southeastern Pennsylvania operated as nominally self-sufficient iron plantations. The ironmaster, founders, fillers, guttermen and colliers (some slaves, some freemen) lived on the plantation with their families. They shopped in company stores, and their children went to company schools. In addition to the furnaces and the “big house,” plantations frequently featured sawmills and gristmills, fields and orchards, stables and corncribs. Perhaps the best documented plantations were those developed by Charles Read (1715-74) of Burlington City and his partners from Philadelphia and New York between 1765 and 1767. They built New Jersey’s Atsion (1765-c.1846), Batsto (1766-c.1850), Etna (c.1766-73), and Taunton (c.1776-c.1830) ironworks. Well-preserved and well-documented ironworks in southeastern Pennsylvania include Hopewell Furnace (1771-1883) established by ironmaster Mark Bird (1738-1812), Cornwall Furnace (1742-1883) established by Peter Grubb (c.1702-54), and Johanna Furnace (1791-1898).

A black and white photograph of the old furnace in Cornwall, Pennsylvania.

The Cornwall Furnace in Lebanon County, Pennsylvania, pictured here, opened in 1742, continued operation into the mid-nineteenth century, and closed in 1883. (Library of Congress)

During the eighteenth century, domestic demand for bar iron, cast iron, and iron products increased while English iron production experienced stresses like Queen Anne’s War (1702-13). In response, mid-Atlantic colonial iron makers invested in a more efficient, indirect method of iron smelting that permitted greater yields than the bloomery forge. By using a blast furnace that operated at a significantly higher temperature, smelters were able to convert iron ore to a stew of molten metal and slag; the liquefied iron could then be drawn off into molds. To produce workable iron like that from a bloomery forge, the molten iron could be further processed in a finery forge and shingled to produce more flexible and ductile bar iron.

The indirect method of smelting was more complicated, required substantially more labor, and initial costs were high, but this indirect smelting process was more fuel-efficient. Using the indirect method, even poor grade ores could be employed to produce high grade iron. To meet the demand of growing markets, during the eighteenth and nineteenth centuries other technologies that increased efficiencies, lowered costs, and expanded the range of domestic and industrial products available were adopted, including the slitting mill, the rolling mill, and the coal-fired puddling furnace. By 1750 American ironmasters became major suppliers of iron to British manufactures and by 1775 they were the third-largest producers of iron in the world.

Iron production in the hinterland provided Philadelphia with plentiful supplies of coal, coke, and pig iron, which supported craftsmen and manufacturers in the city. By 1810 Philadelphia became home to several dozen iron-dependent manufacturing interests—carriage makers, gun factories, naileries, saw factories, and more—as well as several hundred blacksmiths. By the 1870s nearly two hundred fifty blacksmiths and nine hundred manufacturers of iron goods (and one blast furnace) could be found in the city. Manufacturers produced hardware, hollowware, and stoves; steam engines and boiler plate; locomotives and ships; and iron stock (bar iron and sheet iron). Nineteenth-century iron goods manufacturers in and around Philadelphia included the Schuylkill Ironworks at Conshohocken (est. 1837), a rolling mill that produced sheet and plate iron; the Port Richmond Ironworks of I.P. Morris, Towne & Co. on the Delaware, which produced machinery, steam engines, and boilers (est. 1845); the Baldwin Locomotive Works (c. 1831-1920s); and, the William Cramp & Sons Ship and Engine Building Company shipyard (1830-1927).

Although a few iron plantations persisted into the late nineteenth and early twentieth centuries, most were gradually supplanted by the 1840s. In southern New Jersey, difficulties became evident by the early nineteenth century when most ironworks, having exhausted local supplies, had to import both fuel and iron ore by barge. At the same time charcoal-fueled iron production could not compete with newer, more efficient furnaces that employed anthracite and coke-fueled hot-blast technology. Furthermore, while charcoal iron was suitable for products such as agricultural implements and nails, railroads and other nineteenth-century industries preferred more durable hot-blast iron produced with anthracite coal and coke. Iron producers in southeastern Pennsylvania fared somewhat better. The advent of new smelting processes and technologies that employed coal or coke as fuel, together with the discovery of high grade mineral ores in the interior, competition from English producers, and cyclical market fluctuations, caused a gradual shift of the center of the iron industry to the north and west. There, ironworks could be established closer to Pennsylvania’s anthracite and bituminous coal deposits and sources of high-grade mineral ore. Those ironworks in southeastern Pennsylvania that managed to remain competitive into the twentieth century did so by producing technically complex specialty products like boiler-plate, mechanical components, ship hulls, and steel.

At Hopewell Furnace National Historic Site in Chester County, Pennsylvania, the remains of an iron furnace call attention to the region's history in iron production. (Library of Congress)

At Hopewell Furnace National Historic Site in Chester County, Pennsylvania, the remains of an iron furnace call attention to the region’s history in iron production. (Library of Congress)

By the end of the nineteenth century, the last of the charcoal iron forges and furnaces in southeastern Pennsylvania and southern New Jersey were cold and quiet. Even older operations that adopted new technologies and fuels gradually fell to larger, more efficient competitors in the West. By the 1880s the Durham Furnaces  (c. 1850–c.1887) and Bristol Forge (c. 1844–before c. 1878) of Bucks County were shuttered, as well as Merion Furnace (c. 1847-1880) and Norristown Furnace (c. 1869-1874) in Montgomery County; Isabella Furnace (c. 1835-1880) and Hibernia Rolling Mill (c. 1835- before c. 1880) in Chester County; and the Old Sable Iron Works in Delaware County (c. 1808-before 1875). Nonetheless, Pennsylvania’s iron producers and manufacturers remained competitive into the twentieth century by adopting new technologies and developing new products. Not until the latter twentieth century did the widespread deindustrialization of the American economy finally crush iron and iron-goods production in Pennsylvania, destabilizing the economy of entire regions, depopulating once thriving cities, and initiating a decades-long search for ways to reclaim the prosperity that the iron industry once provided.

Brian Albright is a graduate of Rutgers University-Camden and Senior Historian at engineering firm AECOM in Burlington, New Jersey. His interests include the industrial, labor, and social history of Philadelphia in the nineteenth and early-twentieth centuries and the environmental history of the mid-Atlantic region.

Copyright 2016, Rutgers University

Related Reading

Bining, Arthur Cecil. Pennsylvania Iron Manufacture in the Nineteenth Century. Harrisburg: The Pennsylvania Museum and Historical Condition, 1973.

Boyer, Charles S. Early Forges and Furnaces in New Jersey. Philadelphia: University of Pennsylvania Press, 1963.

Durfee, William F. “The Development of American Industries since Columbus: I. Early Steps in Iron Making.” Popular Science Monthly, December 1890, 145-172.

Durfee, William F. “The Development of American Industries since Columbus: II. Iron Mills and Puddling-Furnaces.” Popular Science Monthly, January 1891, 314-338. 

Gordon, Robert B. American Iron, 1607-1900. Baltimore: Johns Hopkins University Press, 1996.

Mulholland, James A. A History of Metals in Colonial America. Alabama: University of Alabama Press, 1981.

Pennsylvania Society of the Colonial Dames of America. Forges and Furnaces in the Province of Pennsylvania. Philadelphia, 1914.

Pierce, Arthur D.  Iron in the Pines: The Story of New Jersey’s Ghost Towns and Bog Iron. New Brunswick: Rutgers University Press, 1957.

Walker, Joseph E. Hopewell Village: The Dynamics of a Nineteenth-Century Iron-Making Community. Eastern National, 2000.


Cyrus J. Sharer research files on the iron ore and steel industries; Lukens Steel Company records; and Brandywine Ironworks and Nail Factory correspondence, Hagley Museum and Library: Manuscript and Archives Department, Greenville, Del.

Phoenix Iron Company records, Historical Society of the Phoenixville Area, Phoenixville, Pa.

Hatfield and Hibernia Park records, Chester County Archives, West Chester, Pa.

Places to Visit

Batsto Village National Historic Site, 31 Batsto Road, Hammonton, N.J.

Hopewell Furnace National Historic Site, 2 Mark Bird Lane, Elverson, Pa.

Cornwall Iron Furnace State Historic Site, 94 Rexmont Road, Cornwall, Pa.

National Iron and Steel Heritage Museum, 50 S. First Avenue, Coatesville, Pa.

4 Comments Comments

  1. No mention of Reading & Warwick Furnaces in Chester County? The role of local Iron making in the revolution etc.?

    Peggy Hartzell Posted March 8, 2017 at 10:56 am
  2. There are of course dozens of local furnaces and forges in southeastern Pennsylvania and southern New Jersey not specifically mentioned in the essay but Reading Furnace is a great example of the historical trajectory of iron production in the region. First built in 1736 the furnace produced hundreds of tons of iron pig until 1778 when it was shuttered. Obsolete and out of blast for eight years, the furnace was then demolished and a forge was built on its foundation in 1786. The furnace remained in operation until 1811 after which iron working at the site was abandoned entirely.

    You are correct in noting the contributions that Philadelphia-area ironmasters made to the Revolutionary War effort. Establishments like Hopewell Furnace successfully contributed supplies of shell, shot, and cannon to the Continental Army despite their previous inexperience in producing munitions. However, because wartime arms production among Philadelphia-area ironmasters was a relatively short-lived phenomenon that was greatly reduced after 1783, it exerted relatively little influence on the overall development of the industry in the region. So while munitions production was of great importance to the American Revolution, it had only a modest influence on the overall developmental history of iron production in southeastern Pennsylvania and southern New Jersey (in my opinion).

    Brian Albright Posted June 20, 2017 at 2:45 pm
  3. Please consider adding Joanna Furnace in Berks County. We demonstrate hand casting as was done here in the 18th and 19th centuries.

    JACK WOODS Posted July 20, 2020 at 10:27 am
  4. Always a history buff and interested in the old and unusual ever since a young boy I recently discovered in Mount Laurel NJ something that peaked my interest. On a 30 acre tract of land , during the building of a new subdivision I was walking fresh leveled land and a portion that still had old forest growth not yet disturbed. I discovered a 20ft high pile of what I thought were moss covered meteors . They ranged in size from bowling ball to basketball. Each one completely encompassed with large pores. I then did some more walking and stumbled into what appeared to be the remains of an old work shed. Knowing a little about everything old I noticed empty whiskey bottles that dated circa 1935. In this area I noticed a piece of old iron in which only only about 4 inches were exposed and the rest appeared to be buried. Well I had to find out what it was ! I got a shovel and went down into the marl / soil about 2 ft and there were two 6ft by 5ft farm tillers ? These were made for horses to pull and still in very good structural condition. Upon examination it occured to me that these were iron and very early. I then did some reading and discovered that one of the qualities of bog iron is its ability to deter rust as mentioned these were in good condition. I feel that these are extremely heavy for their size. In summary there had to be some type of iron forge on this tract of land. The 20ft pile of porous rocks I believe was slage which were trucked away . I kept about 20 of them. I was about 64 yrs old when I pulled those tillers out and now being 67 they are in my backyard and quite frankly I have no idea how I moved them due to their weight . I carried each one the equivalent of a city block through the woods. There was a grand historic home and a farm on the property but that was over 25 years ago. Word has it that the inventor of the stethoscope lived in the home ? The point of this whole story is that there was an early iron foundry in Mt Laurel NJ that is not recorded in history. Another note ! the streams adjacent to this area run orange with iron and I have noticed these slag rocks used as support on the main road around the creek pipe. The rocks and tillers are in my backyard if anyone wants take a look ! Thanks for this site

    EDWARD MALESINSKI Posted April 18, 2021 at 11:23 am

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