The Gunpowder Copper Works, a once-prominent factory located along the Great Gunpowder Falls near Glen Arm, Maryland is the second oldest copper works in the United States. The factory operated from around 1811 to 1858 turning blocks of copper into thin sheets used for covering the bottoms of ships and boats to increase their speed and durability. Possibly the most intact industrial site of its kind along the Great Gunpowder Falls, the factory is located immediately past Factory Road on northbound Harford Road.
The Gunpowder Copper Works was established around 1811 by Levi Hollingsworth, a veteran of the American Revolution and a prosperous merchant from Cecil County with major investments in shipbuilding. On a trip to England, Levi Hollingsworth studied the refining, milling and rolling of copper and brought back extensive machinery he needed to set up a factory in America. He likely established the factory soon after leasing a mill from Dr. Thomas Love and Caleb Dorsey Goodwin on this site in 1811.
The Copper Works factory complex included two sets of sheet rolls, two refining furnaces, and later, and a cupola furnace for treating the slag. A water-wheel furnished the power. With a factory among in the fertile hills of Baltimore County, workmen eventually took to farming when business slowed. When the crops needed attention, workers left rolling and milling for another day.
During the War of 1812, the Gunpowder Copper Works supplied the U.S. Navy with sheathing, bolts and nails. Levi Hollingsworth joined the Fifth Maryland Regiment in 1814 and was wounded in September fighting the British at the Battle of North Point.
Shortly after end of the war, the dome on the U.S. Capitol in Washington, D.C. was rebuilt using copper sheathing rolled by the the Gunpowder Copper Works using ore mined in Frederick County, Maryland. The Capitol Dome contract brought the mill national recognition as a copper supplier. The profit from the project allowed Levi Hollingsworth to buy out the Ridgely and Goodwin interests in the Gunpowder Copper Works in 1816. By the time Hollingsworth died 1822, the mill was the only copper refinery in operation south of the Mason-Dixon Line. By 1850, the Gunpowder Copper Works had produced between 550,000 and 1.5 million pounds of copper sheeting.
After Levi Hollingsworth's death, the Copper Works sold to John McKim, Jr. and Sons. Operation of the copper works continued under the management of Isaac McKim until his death in 1838. Isaac McKim linked the Gunpowder Copper Works to the family's shipbuilding supply business on Smith's Wharf in Baltimore's harbor, now the site of the National Aquarium.
After Isaac's death, his nephews bought out the other beneficiaries and ran the Copper Works. Haslett and William McKim were both active businessmen in Baltimore, serving on the boards of the Baltimore Dispensary, the Peabody Institute, the B&O Railroad, and the Maritime Insurance Company. William McKim served as an aide-de-camp to Commander John Spear Smith during the Baltimore Bank Riot in 1835. His uncle, Isaac, had served a similar position to Commander Smith's father, General Sam Smith, during the War of 1812.
In September 1843, a notice in the Baltimore American, advertised the copper works for lease including:
"a sheet mill with two pairs of rollers, two pairs of large shears operated by a water wheel, two annealing furnaces, a tilt and bolt mill, a tilt-hammer operated by a water wheel, two furnaces, a blacksmith shop, carpenter and turning shop and a nail machine. Two refining shops with a slag furnace, coal houses and homes for workmen. The Dam is substantial and in good condition, and the water power is among the best in the vicinity of Baltimore. The works are on a good turnpike about 10 miles above Baltimore."
In 1858, major rain storms in mid-June caused significant flooding in the area and along the Great Gunpowder Falls, which destroyed the dam at the Copper Works. The dam was rebuilt, but operation ceased later that year and the factory closed. The owners rented the property rented to a tenant operator in 1861 but it likely remained closed during the Civil War. The Maryland General Assembly incorporated the Gunpowder Copper Works as a state facility in 1864, naming Levi Hollingsworth's son-in-law, William Pinkney Whyte, president of the operation, and Enoch Pratt, one of the incorporators. Despite Whyte's prominence as a politician and Pratt's success in business, the newly incorporated copper works soon failed. The City of Baltimore bought the 303 acres of land on which the copper works sat in 1866 as the possible site for a future reservoir.
In 1887, the Baltimore City Water Board sold the copper works to Henry Reier, who sold it to Henry E. Shimp for his "bending works at the Old Copper Factory on the Gunpowder," where he manufactured wheel rims, wagon-wheel spokes and wagon shafts. The facility never processed copper again, but Shimp's Eagle Steam Saw and Bending Mills continued operating into the twentieth century.
J. Alexis Shriver, Harford County landowner, bought the property in 1910 and sold the plant's water wheels during a World War I scrap drive. By the mid-twentieth century, the facility stood in ruins but was acquired by the state as part of the new Gunpowder Falls State Park.
There are at least four buildings from the original complex still standing along Harford Road just above Gunpowder River bridge. These include the Copper Works House with outbuildings, the Tilt-hammer House, the Foreman's House, and the spring house and bridge.
Constructed about 1815, the Gunpowder Copper Works House is a one-and-a-half-story stone building reportedly used as a dormitory for the workers at the nearby plant. By about 1900, this building had been converted to a stable by J. Alexis Shriver then later converted to a residence. The small stone Foreman's House was built around 1815. Two more stories and a large shed dormer were added to the building later. The house sold to Henry Reier in 1877 and his family held it until 1938. The Tilt-hammer House, built about 1815, may have been the coppersmith's house at one time. When it served as the tilt-hammer house, this building is where copper was pounded into sheets. The building became a residence after 1925 and the only original parts of the structure are the exterior stone walls.
Today, all of these buildings are in use as residences or offices. They are located within the Gunpowder Historic District and sit on land which has been incorporated into Gunpowder State Park.