Iron Mining and Metallurgy

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Iron mining, refining, and manufacturing were at the core of early American industrial development. The iron industry was both the most capital-intensive to develop and the most potentially lucrative business venture in the British colonies of North America. Interest in locating deposits of iron, extracting the ore, smelting it, and refining it was evident in the earliest permanent settlements. Small amounts of ore were found in Virginia in 1608 and sent back to England for refinement. A bloomery (a small, enclosed kiln used for roughly smelting iron) was established in the colony at Falling Creek by 1622, although it was destroyed in the Powhatan rising in the same year. In 1641 John Winthrop, Jr., proposed the construction of a complete ironworks in Massachusetts, including a blast furnace (where iron ore was initially smelted into liquid and turned into large bars, called pigs), fineries (a large hearth where pig iron was reheated into a softened mass called a "half-bloom," from which larger impurities were hammered and chipped out manually or by means of a triphammer), and chaferies (a smaller hearth where the iron was again heated and drawn into thinner bars, which were continually rubbed and redrawn until all visible impurities were eliminated). By 1643 a company was formed in London to finance the Massachusetts works. In 1644 construction of the works on the Saugus River began, and more than one hundred experienced ironworkers were imported to carry on the operations.

In the 1650s and 1660s ironworks were established in Massachusetts, Connecticut, and Delaware. But these iron companies were expensive to build and maintain. Because the cost of transatlantic transportation in the period was high, with few local markets available, all of these early operations fell into severe financial difficulties and eventually failed. The first profitable iron company in the English colonies was founded by Lewis Morris at Tinton Falls, New Jersey, around 1680, followed by others in Maryland and Pennsylvania. By the turn of the eighteenth century, establishing a viable and profitable iron industry in the colonies became easier for several reasons. First, the settlement and stabilization of more than fifteen colonies from New England to the West Indies after 1630 created a much larger market network in the Americas that could support iron manufacture. Second, after 1660 more ships were built for transatlantic shipping and regulation increased, greatly reducing shipping costs and making exportation of pig iron from the colonies to England at least minimally profitable. Third, the expansion of trade under the English mercantile system beginning in the mid-seventeenth century aided in enriching a significant number of colonial merchants and their families. These merchants, seeking to diversify their interests, had the capital to finance the building and expansion of dozens of new ironworks. Fourth, and perhaps of the greatest importance, local populations grew rapidly in the colonies, continually expanding local markets for iron and iron goods. These local and regional markets along the Atlantic coast were keys to the profitability of the iron industry, as nearly 80 percent of the iron produced in the British colonies of mainland North America was sold on the mainland.

Not all iron manufacturing operations were successful. At a cost of between £10,000 and £50,000 in the eighteenth century, depending on the size and complexity of the ironworks, problems with resources, labor, transportation, weather, competition, or any combination of these factors could spell disaster. Nearly half of the ironworks established in the six decades prior to the American Revolution failed less than twenty years after they were founded. Others, however, would last nearly a century.

land and resources

Iron ores, including red and brown hematite, magnetite, and carbonate can be found throughout southern Virginia through western and northern Maryland, Pennsylvania, and New Jersey, and in the colonial period could be found widely across the land's surface. The visible abundance of iron deposits, as well as limestone deposits (used as flux in charcoal iron manufacture), were the first indicators that profitable extraction and refining were possible. But iron ore and limestone deposits were not enough. Fueling even a small ironworks required a large area of forest, as charcoal production was a necessary step preliminary to the smelting process. A colonial blast furnace produced approximately 400 tons of pig iron per year (2 tons of ore could be smelted into 1 ton of pig iron), with each ton requiring between 100 and 120 cords of wood as fuel. Hardwoods burned hottest and were most efficient, softwoods less so. An acre of forested land yielded an average of 20 usable cords of wood, and would take a minimum of twenty years to replenish, if conservation was followed. An iron plantation needed 4,000 to 5,000 acres of forested land in order for production to continue for more than twenty years. The average iron company operated on 5,400 acres.


The availability of much surface ore in the early eighteenth century kept mining operations fairly basic before mid-century. Miners dug shallow trenches, following the visible lines of ore and extracting the most accessible iron. Under these conditions four to six miners could dig a sufficient amount of ore per day (three to four tons) to keep a furnace in operation. The deeper the trenches were cut, the more labor was necessary, as impacted ore was harder to extract and required additional workers to hoist the ore out of deeper trenches and keep the pits clear of water.

Although technologies did not change, by 1750 most iron companies that had been in operation for two decades or more were operating what could be more accurately called mines. Mine holes forty to fifty feet deep required eight miners to produce the same daily tonnage as six had done from a surface trench, and at least one winch operator was needed to hoist water from the hole. By the 1770s and 1780s, long-established operations were beginning to move toward shaft mining to access deeper veins of ore. This was more costly and dangerous, as it required more labor as well as blasting. Shaft mines had to be shored up by wooden palisades in order to prevent regular collapses. Accidents were still fairly regular and the narrow shafts, typically less than a hundred feet deep, did not allow for rescues of men trapped by flooding waters or cave-ins.

Miners in the last quarter of the eighteenth century were typically skilled both in locating profitable veins deeper in the earth and the art of gunpowder blasting. Men whose higher wages were based on skill were called masters, and laborers who actually did the digging were often called helpers. Higher wages for skilled workers and the need for more labor increased the cost of production after the mid-eighteenth century. Britain still needed American iron, but its value decreased as its production costs increased. Parliament, through regulation, tried to keep colonial iron competitive with Russian and Swedish iron sources, but this became more difficult over time.

british regulation

Many Americans viewed the British mercantile system as restricting, and at times it was, but it was always intended to benefit both the home country and the colonies. In the field of iron production, parliamentary allowances were historically generous. Parliament routinely voted down bills that would have raised the import duties for pig and bar iron and outlawed the manufacture of ironware in the colonies. This policy allowed for colonial iron to enter England competitively compared to foreign exporters' iron. Also, owing to the prohibitive cost of establishing and running a blast furnace in the colonies, to prevent ironmasters from refinement beyond initial smelting or a prohibition on ironware manufacturing would have eliminated any profit incentive for colonial entrepreneurs.

In 1750, however, a new iron act was passed in reaction to the great expansion of ironware manufacture in the colonies, which was drastically reducing imports from England. Pot ware (kettles, pots, pans), wrought iron, and stove plates of colonial manufacture covered almost all of the American market; of even greater concern, the proliferation of steel furnaces, plate mills (producing sheet iron), rolling and slitting mills (producing rods), naileries, and wire mills were eliminating local need from British manufacturers. In exchange for elimination of all duties on American iron brought into England, the Iron Act of 1750 banned the new construction of any of these operations in the colonies.

No one on either side of the Atlantic was satisfied with the 1750 act. British manufacturers wanted existing colonial mills shut down, and colonial entrepreneurs saw the regulation that barred them from tapping into an expanding market for goods as unfair. In the end, the inability of the British government to enforce the act made it essentially moot. American iron manufacturing had come too far in the half-century prior to 1750 to stop cold. Colonial ironmasters took the stance that, rather than fighting for the repeal of the act, they would ignore it. Not only were preexisting iron mills underreported by at least 75 percent, between 1752 and 1775 five new steel furnaces, five naileries, four slitting mills, three plate mills, and three wire mills were built in Pennsylvania alone. In the mainland colonies as a whole, more than sixty operations made illegal by the Iron Act of 1750 were constructed in defiance of parliamentary regulation.

Independence requires both a belief and a practical demonstration that one can stand on one's own. In the business of iron manufacturing in British America, that belief and demonstration began to appear soon after 1750.

In many ways, both independence and available resources hampered technological expansion in the U.S. iron industry in the half-century after the Revolution. By the early 1790s, Congress regularly passed tariff legislation to protect the iron industry from foreign competition. This kept the price of iron and iron products high enough in the domestic market for U.S. companies to maintain profitable businesses, but most were unwilling to invest capital in newer technologies before the 1840s. The application of steam power technology, expanding in other U.S. industries, was universally ignored in the iron industry for decades. U.S. iron manufacturers held to charcoal blasts long after coke was employed as a cheaper fuel source internationally. The rationale for this was based on the availability of seemingly endless forests on the western frontier. Iron manufacturers generally abandoned older works situated one hundred miles or less from the Atlantic coast and set up newer works to the west—in upstate New York, the Alleghenies of Pennsylvania, eastern Ohio, the northwestern counties of Virginia, and eastern Tennessee—still applying seventeenth- and eighteenth-century techniques.

This attitude damaged the ability of U.S. iron manufacturers to compete effectively in the international iron and steel markets. It was only the rapidly expanding domestic market the allowed iron makers to profit. One of the highest rates of natural increase in the world and high immigration figures swelled the population in the early nineteenth century. Urbanization, particularly after 1815, expanded markets for iron goods for construction as well as potware and utensils.

U.S. iron manufacturers might have continued for decades longer without change had it not been for the advent of railroads. Between 1835 and 1850, it became clear in the first flurries of railroad building that the quantity and quality of U.S. iron was insufficient to meet the needs of expansion. The needs of railroads to tie the growing United States together, along with the realization that forests were a finite resource, forced iron makers to modernize.

See alsoManufacturing; Work: Overview; Work: Unskilled Labor .


Bining, Arthur C. British Regulation of the Colonial Iron Industry. Philadelphia: University of Pennsylvania Press, 1933.

——. Pennsylvania Iron Manufacture in the Eighteenth Century, 2nd ed. Harrisburg: Pennsylvania Historical and Museum Commission, 1973.

Bruce, Kathleen. Virginia Iron Manufacture in the Slave Era. New York: Century Company, 1930.

Paskoff, Paul F. Industrial Evolution: Organization, Structure, and Growth of the Pennsylvania Iron Industry, 1750–1860. Baltimore: Johns Hopkins University Press, 1983.

Temin, Peter. Iron and Steel in Nineteenth-Century America: An Economic Inquiry. Cambridge, Mass.: MIT Press, 1964.

Michael V. Kennedy