The technological development of the US iron and steel industry has closely mirrored that of other countries. In the 1800s, the US switched from charcoal to coal in ore smelting, adopted the Bessemer process, and saw the rise of very large integrated steel mills. In the 20th century, the US industry transitioned from the open hearth furnace to the basic oxygen steelmaking process. After peaking in the 1940s and 1950s, the US iron and steel industry shifted toward smaller mini-mills and specialty mills that use iron and steel scrap instead of iron ore.

Colonial

Before the 19th century, iron production relied on charcoal. However, Britain’s once-abundant forests could no longer meet the nation’s growing demand for iron.

By 1700, Britain was becoming increasingly dependent on iron imported from its sometimes-adversary Sweden. Britain looked to the seemingly limitless forests of its American colonies to supply Britain with iron. British investors started an iron furnace near Perryville, Maryland, which in 1718 started exporting iron back to Britain. That success prompted formation of more companies, which built numerous iron furnaces around Chesapeake Bay, supplied by bog iron ore, which was widespread. By 1751, Virginia and Maryland were exporting 2,950 tons of pig iron to Britain each year; at the time, British iron production was about 20,000 tons per year.Norman J. G. Pounds and William N Parker, Coal and Steel in Western Europe (Bloomington: Indiana Univ. Press, 1957) 22.

While the Chesapeake Bay furnaces were established for export, iron furnaces were established in the 1700s throughout the American colonies for domestic consumption. Iron furnaces were located along rivers to supply water power. Also required were forests for charcoal, iron ore, and limestone for flux. In addition, the furnace needed to be close to a major market or close to water transport.

British business interests were split on colonial iron: manufacturers appreciated the lower prices due to colonial imports, but the British iron and steel industry objected to the competition. Parliament compromised in the Iron Act 1750, which eliminated the import duty on colonial pig iron, but barred the manufacture of steel or of iron plate in the colonies. Despite the Iron Act 1750, colonial governments continued to develop their iron industries.

By 1776, up to 80 iron furnaces throughout the American colonies were producing about as much iron as Britain itself. If one estimate of 30,000 tons of iron each year is accurate, then the newly formed United States was the world's third-largest iron producer, after Sweden and Russia.

Notable pre-19th-century iron furnaces in the US Name Location Start date End date Boonton Iron Works Boonton, New Jersey circa 1770 1911 Catoctin Furnace Catoctin Furnace, Maryland 1774 1903 Falling Creek Ironworks Chesterfield County, Virginia 1622 1622 Furnace Mountain Loudoun County, Virginia circa 1790 circa 1870 Hunter's Ironworks Falmouth, Virginia circa 1750 1782 Huntingdon Furnace Huntingdon County, Pennsylvania 1796 circa 1880 Neabsco Iron Works Woodbridge, Virginia circa 1737 New Roxbury Ironworks Site Woodstock, Connecticut 1757 Patuxent Iron Works Anne Arundel County, Maryland 1705 1856 Principio Furnace Cecil County, Maryland 1719 1925 Saugus Iron Works Saugus, Massachusetts 1646 circa 1670 Stirling Iron Works Monroe, New York 1761 1842 Taunton Iron Works Raynham, Massachusetts 1656 1876 Washington Iron Furnace Rocky Mount, Virginia circa 1770

Early republic

Because wood for charcoal was available throughout the eastern states, iron smelters were located close to iron ore. Although the bog iron ores mined in colonial days were widespread, the deposits were also small, and quickly exhausted. In the late 1700s the iron furnaces moved away from the bog iron ore of the coastal swamps, to larger iron ore deposits further inland. Inland locations also allowed the furnaces to be closer to sources of limestone, which was used as a flux in iron smelting. The proximity to larger ore deposits favored larger, more permanent iron smelters.US Geological Survey, 2001, Silent reminders, Geologic Wonders of the George Washington and Jefferson National Forests, No. 3.

Most US iron smelting before 1850 took place near iron deposits in eastern Pennsylvania, New York, and northern New Jersey.John S.Brown, "Ore deposits of the northeastern United States," in, John D. Ridge (ed.), Ore Deposits of the United States, 1933-1967 (New York:American Institute of Mining Engineers, 1970) 2-4. New Jersey's principal iron ore district, at Dover, supported iron smelters beginning in 1710. The Cornwall Iron Furnace in Pennsylvania was established next to an iron deposit. The Adirondack iron ore district of New York also supported iron smelters.Martha S. Carr and Carl E. Dutton, 1959, Iron-Ore Resources of the United States, Including Alaska and Puerto Rico, US Geological Survey, Bulletin 1082-C, p.66-67.

The movement away from charcoal in US iron smelting began in 1827, when a puddling furnace in Phoenixville, Pennsylvania started using anthracite coal. Blast furnaces continued to use only charcoal until about 1840, when coke from coal started replacing charcoal as the fuel and reducing agent.James M. Swank, "The manufacture of iron and steel in the United States," in: Mineral Resources of the United States, 1883 and 1884, US Geological Survey, 1885, p.247. Coke has a higher crushing strength than charcoal, allowing larger smelting furnaces.W. H. Dennis, 100 Years of Metallurgy (Chicago: Aldine, 1963) 79-80. Because iron and steel-making at the time consumed more coal than iron ore, the steel mills moved closer to the coal mines to minimize transportation costs. A problem of coke was that it carried impurities such as sulfur, which degraded the quality of the steel. Although coke quickly became the dominant fuel for iron-smelting, in 1884 charcoal was still used to make ten percent of iron and steel in the US. The use of charcoal for steelmaking survived in the US on a small scale until 1945.

The Lackawanna Valley in Pennsylvania was rich in anthracite coal and iron deposits. Brothers George W. Scranton and Seldon T. Scranton moved to the valley in 1840 and settled in the five-house town of Slocum's Hollow (now Scranton) to establish an iron forge.Yeomans, "36 Hours: Scranton, Pa.," New York Times, November 1, 2002."The Bitter Battle," Time, October 19, 1962. The most common processes for creating blister steel and crucible steel were slow and extremely expensive. The Scrantons instead used the new "hot blast method," developed in Scotland in 1828. The hot blast method solved the problem of impurities from the coke, by burning them off. The Scrantons also experimented with anthracite to make steel, rather than charcoal or bituminous coal.Lewis, "The Early History of the Lackawanna Iron and Coal Company: A Study in Technological Adaptation," Pennsylvania Magazine of History and Biography, October 1972.

The replacement of charcoal with coal in the steel-making process revolutionized the industry, and tied steelmaking to coal-mining areas. In the 1800s, making a ton of steel required a greater weight of coal than iron ore. Therefore, it was more economical to locate closer to the coal mines. Pittsburgh, Pennsylvania, surrounded by large coal deposits and at the junction of three navigable rivers, was an ideal location for steelmaking.

Notable early 19th-century iron furnaces in the US Name Location Start Date End Date Bradys Bend Iron Company Furnaces Armstrong County, Pennsylvania 1840 1873 Catherine Furnace Newport, Page County, Virginia 1836 1885 Curtin Village Centre County, Pennsylvania 1810 1921 Elizabeth Furnace Fort Valley, Virginia 1836 1888 Georges Creek Coal and Iron Company Lonaconing, Maryland 1837 1855 Isabella Furnace Chester County, Pennsylvania 1835 1894 Joppa Iron Works Baltimore County, Maryland circa 1817 circa 1865 Longdale Furnace Historic District Clifton Forge, Virginia 1827 Mount Savage Iron Works Mount Savage, Maryland 1837 circa 1870 Nassawango Iron Furnace Site Snow Hill, Maryland 1830 1849 Richmond Furnace Historical and Archeological District Richmond, Massachusetts 1829 1923 Roaring Run Furnace Eagle Rock, Virginia 1832 Scranton Iron Furnaces Scranton, Pennsylvania 1848 1902 Tredegar Iron Works Richmond, Virginia 1837 circa 1950

Rapid growth, 1856–1940 In 1856, Englishman Henry Bessemer invented the Bessemer process, which allowed for mass production of steel from molten pig iron, reducing the cost of making steel by more than 50%. The first American steel mill to use the process was constructed in 1865 in Troy, New York. In 1875, the largest-yet steel mill, Edgar Thomson Steel Works in the Pittsburgh area, was built to use the Bessemer process, financed by industrialist Andrew Carnegie.

The tremendous iron ore deposits around Lake Superior were located far from coal deposits, and so were shipped to ports on the southern Great Lakes that were closer to the coal mines of Pennsylvania, Ohio, Indiana, and Illinois. Large integrated steel mills were built in Chicago, Detroit, Gary, Indiana, Cleveland, and Buffalo, New York, to handle the Lake Superior ore.

Cleveland's first blast furnace was built in 1859. In 1860, the steel mill employed 374 workers. By 1880, Cleveland was a major steel producer, with ten steel mills and 3,000 steelworkers.Iron and steel industry, Encyclopedia of Cleveland, accessed 5 Nov. 2015.

The city of Gary, Indiana was founded in 1906 by United States Steel Corporation to serve the Gary Works.

The Lackawanna Steel Company built a large integrated steel works near Buffalo, which began producing steel from Lake Superior ore in 1903. The company had made steel in Scranton, Pennsylvania since 1840, but moved to provide easier access to iron ore, and in an unsuccessful attempt to avoid labor troubles.

Birmingham, Alabama became a major steel producer in the late 1800s, using locally mined coal and iron ore. The iron ore was mined from the Red Mountain Formation of Silurian age.

Notable defunct late 19th-century iron and steel furnaces in the US Name Owners Location Start Date End Date Antrim Iron Company Mancelona, Michigan 1886 1945 Bellefonte Furnace Bellefonte, Pennsylvania 1888 1910 Bethlehem Works Bethlehem Steel Bethlehem, Pennsylvania 1857 1995 Brierfield Furnace Brierfield, Alabama 1861 1894 Callie Furnace Glen Wilton, Virginia circa 1873 1884 Cornwall Furnace Cedar Bluff, Alabama circa 1862 1874 Endor Iron Furnace Cumnock, North Carolina 1861 1971 Fayette Historic State Park Fayette, Michigan 1867 1891 Homestead Steel Works Carnegie Steel, US Steel Homestead, Pennsylvania 1881 1986 Janney Furnace Park Ohatchee, Alabama 1863 1864 Nittany Furnace Centre County, Pennsylvania 1888 1911 Oregon Iron Company Lake Oswego, Oregon 1867 1893 Sloss Furnace Birmingham, Alabama 1882 1971 South Works US Steel Chicago, Illinois 1857 1992 Sparrows Point, Maryland Bethlehem Steel Baltimore County, Maryland 1889 2012

World War II and after

As the only major steel maker not harmed during World War II, the United States iron and steel industry reached its maximum world importance during and just after World War II. In 1945, the US produced 67% of the world's pig iron, and 72% of the steel. By comparison, 2014 percentages were 2.4% of the pig iron, and 5.3% of the steel production.

Although US iron and steel output continued to grow overall through the 1950s and 1960s, the world steel industry grew much faster, and the US share of world production shrank. In the 1960s, the US became a major importer of steel, mostly from Japan.

Contraction: 1979–1984