NJ iron mines cause sinkholes. They were also key to revolution

While many New Jerseyans think of the state’s history of mining as the cause of sinkholes that appeared on Route 80 last year, these ore-rich underground tunnels were also critical to the Revolutionary War and the state’s early economic success.

Ironworks and mines for other minerals, such as zinc, helped establish small towns in 1700s-New Jersey, and they eventually became key to supplying American patriots with cannons and cannonballs to fight the British.

Iron was largely used to support farming in the Garden State, New Jersey’s nickname because of its agricultural history. That ore and those skills became useful once the Revolutionary War started, said William Kroth, an engineer and executive director of the Sterling Hill Mining Museum in Ogdensburg.

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“Plows, horseshoes, nails to build your barn, vises, you name it — you go to a farm, it’s not just growing things. You need things that are hard, things that could do work for you, and iron was great,” Kroth said. “If you’re fighting an army, you need armament and cannons, cannonballs, rifles — all used iron back then.”

The American colonies — mainly New Jersey, Pennsylvania and Virginia — had become the world's third-largest producer of iron by 1775, said Kathryn Reuter, a fine arts librarian of Penn Libraries at the University of Pennsylvania, who wrote about the topic earlier this year.

“Without this artillery, the American Revolution could have been quashed by British forces,” Reuter wrote.

“Just as important, however, American iron workers built a strong foundation for the young country’s economy," she wrote. "The success of ironworks proved the ability of the young colonies to be an industrial powerhouse on the global scale.”

British moved to control iron in colonies

New Jersey’s vast and bountiful natural resources, especially its iron-rich mountain ranges, made North Jersey the largest supplier of iron to the nation until the 1880s, said William Truran, a Franklin resident and Sussex County historian, author and engineer.

During British rule of the American colonies during the 1700s, everyone wanted a piece of the iron economy, said Truran, who is a descendant of New Jersey miners who came from Cornwall, England, where tin and copper mining date back more than 2,000 years.

The Iron Act of 1750 was among the oppressive laws imposed on colonies by the British. It “sought to encourage the production of iron in America, but to discourage its manufacture into finished wrought iron goods,” said Peter King, a historian who wrote a paper about the Iron Act in the Historical Metallurgy publication in 2023.

The intention of the law was to allow American colonies to export iron, and then it would be manufactured in Great Britain into items, such as utensils, hinges, horseshoes, nails and cannonballs, thereby limiting that kind of manufacturing in America — especially potential armaments.

The British "wanted the ore to go to Britain so Britain could manufacture the parts rather than us do it here,” Truran said. "Of course, Americans said we can mold pig iron, do this or that here — and of course they didn’t want us to make cannonballs here, either, for obvious reasons."

The attempt to restrict certain types of mills and iron manufacturing wasn’t very successful in the colonies, especially in New Jersey, King said.

“An additional slitting mill was built in defiance of the law by Samuel Ogden of Newark, NJ at Old Boonton, NJ. When visited by Governor Franklin on the rumour of its existence, Ogden hospitably entertained the governor, who left feeling glad that the report was groundless,” King wrote, referring to William Franklin, New Jersey's last royal governor.

The Iron Act, the Stamp Act of 1765, which taxed Americans’ printed materials, and the Molasses Act of 1733, which taxed Americans’ import of sugar, molasses and rum, all fueled resentment of the British by American colonists.

Sussex County mines targeted

Once the Revolutionary War started in 1775, iron mines and mills were targeted by troops and locals on both sides to ensure access to these valuable sites.

William Potts built what was known as “Franklin Furnace” in 1765 near Franklin Pond, but he eventually got “run out of town” because he was an English sympathizer, Truran said.

Joseph Sharp founded an iron forge and furnace on the Wallkill River in present-day Hamburg in 1768, but he abandoned it in 1774. It was taken over by Stephen Ford, who “used it to secretly produce cannonballs for the British during the American Revolution,” says a historical sign marking the area, off Route 23 on Gingerbread Castle Road.

William Allen and Joseph Turner owned ironworks sites in Sussex and Hunterdon counties. In 1760, they started the Andover Iron Works company, using slave labor, and “set the standard” for the best quality iron in the country, says Kevin W. Wright’s book “A History of the Andover Iron Works — Come Penny, Go Pound.”

However, Allen and Turner were loyal to the British, so the Continental Congress confiscated the Andover mines, forges and furnaces in 1778, and soon iron was mined and manufactured for the patriot cause.

“George Washington’s encampment at Morristown, New Jersey, was in part to protect these works from falling into British control,” reads a historical sign marker at Main Street, or Route 206, and Grist Mill Lane in Andover.

In Hunterdon County, Allen and Turner’s bookkeeper, Robert Taylor, took over the duo’s Union Ironworks operations after they fled because of their loyalty to the British.

Taylor, however, was an Irish immigrant and supported the patriots. He used the foundry cast cannonballs for the revolutionary forces, and Taylor managed the distribution of weapons to the troops in New Brunswick by traveling at night to avoid detection, says an nj.com article.

How the Pine Barrens contributed to iron production

South Jersey’s Pine Barrens also had a thriving iron industry thanks to iron-rich streams, forests for charcoal, and clam and oyster shells that contained lime necessary for the iron-making process.

The British launched an attack on Batsto, a once-prosperous industrial village near Hammonton, in October 1778 to try to gain control of the bog iron industry, said Barry Brady, an archeologist and former Pinelands Commission cultural resource specialist who authored a brief fact sheet about the history of iron production in the Pinelands.

The British attack on Batsto "precipitated the tragic Chestnut Neck Massacre in which a detachment of over 40 Americans was wiped out by the advancing British who quickly withdrew when they learned of a stronger American force in the area,” Brady wrote.

How to visit

There are a number of museums, markers and preserved historical sites around the state that provide more information on New Jersey’s history of mining, iron production and villages that sprang up around this ore.

Here is a brief list of places to visit:

• The Sterling Hill Mining Museum in Ogdensburg provides tours of zinc mines and a museum of minerals, miners’ lockers and other artifacts. It has a mine run dump for rock collectors and has old machine equipment on display.
• The public can visit Batsto Village, which was preserved and includes an operational 1852 post office, 19^th-century water-powered sawmill and 36-room Victorian mansion.
• The Franklin Mineral Museum has hundreds of specimens and fluorescent minerals, a display of Native American tools, and life-size examples of mining-related tools, such as cap lamps, mill concentrates, pig iron and artifacts from Thomas Edison’s mining and milling operation on Sparta Mountain.
• The Andover Iron Works site historical markers and grist mill house at Main Street (Route 206) and Grist Mill Lane.
• Long Pond Ironworks State Park in Hewitt has a museum and sprawling state park with opportunities to hike, fish, go boating and see historical industrial remnants, such as stone walls, furnaces and waterwheels, from the ironworks community formed there in the 1700s. It also has ties to the Revolutionary War and other historical periods.
• The Joseph Turner House and Solitude House museum in Hampton are dedicated to the history of the Union Iron Works and have tours about the origins of the iron industry in Hunterdon County.

This article originally appeared on NorthJersey.com: NJ iron mines cause sinkholes. They were also key to Revolution