John A. Roebling's Sons Company Upper Works
Ghosts of the Wire Industry: Inside Trenton's Roebling Complex
The first fence I found, I didn't jump.
I had parked at the edge of the old industrial park and started walking the block, looking for a seam. That's the work. You circle the property, you read the edges, you find the spot where the chain link has been peeled back, or the post has gone loose. I found one almost immediately, a low fence, nothing to it. Then I noticed the man across the street watching me. So I kept moving, hands in my pockets, just a guy who'd taken a wrong turn.
A few doors down, a commotion. Two people arguing in the middle of the street, loud enough that I slowed without meaning to. It ended the way those things usually end, with nothing settled. The man stepped back onto the sidewalk and then disappeared into the side of the building. Not through a door. Through a gap in the fence I couldn't see from where I stood.
That told me two things. There was another way in. And I wasn't going to take it thirty seconds behind him.
I kept walking, turned left, kept reading the fence line. And there it was. Another section pulled back, and behind it, cut into the weeds, a path.
Not a thin track. A road. The weeds were beaten flat and beaten wide, packed down by months of feet going in and coming out. You learn to read a path like that. It doesn't mean somebody got curious once. It means people. Every day. Enough of them that the ground gave up.
I walked past like I was lost, made a U-turn, and stepped through it like I was walking into my own front yard.
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| Ground floor of Flat Shop No. 3A |
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| Can you spot the hidden tent? |
Inside the Flat Shops
I went straight for the nearest doors, and my senses were up around my ears the whole time, because I already knew what the path meant. Somewhere in those red brick buildings, people were living.
The ground floor of Flat Shop No. 3A, built in 1924, is held up by mushroom columns. That's the actual name for them. Concrete piers that flare out at the top like a stem opening into a cap, spread wide so they can carry the weight of the floor above without a forest of beams getting in the way. Stand among them, and the room feels like something grown rather than built. I set up and started shooting.
Then I looked up, and there was a grey tent shielded by a clothesline of blue tarp.
Ten feet off the floor, pitched on top of a narrow steel gantry pillar, zipped shut. Nobody home, as far as I could tell. I stood there a while trying to work out how a person gets a tent up there, and then how a person gets themselves up there, at night, sober or not. I never did figure it out.
Upstairs, the floor opened up into one long room with windows on every side, and the light came in from all of it at once. I remember thinking it must have been a good place to work. Not easy. Loud, hot, dangerous. But the views were something.
The stairs kept going past the roof, which made no sense to me until later, when I looked back from the next building over and saw what I'd been standing in: a shaft of six or seven flights stacked on top of each other, sealed off from the floors it served. A strange thing to build. I still don't know why they did.
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| The staircase well was taller than the actual Flat Shop No. 3A. |
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| One single rolling mill in 1890 to a massive complex running from the Delaware & Raritan Canal to Hudson Street in the 1920s. |
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| 1893 Rope Room Overlooking 80-ton Rope Machine Photo Courtesy of Library of Congress |
The 200 Acre Behemoth of the Roebling Dynasty
They were built for rope. That's the short version, and it's worth knowing before you walk another step through those rooms.
John A. Roebling came over from Germany in 1831. He had studied bridge engineering in Berlin, which did him no good at all when he first tried farming outside Pittsburgh. He got out of farming and into engineering, working as an assistant on a canal that had to cross the Allegheny Mountains. In the 1830s, canal boats went over those mountains on inclined railways, hauled up by hemp rope. Hemp rope frays. Hemp rope snaps. It wore out constantly, and everyone accepted that, because what else was there?
Roebling had seen wire used for cables back home. So he started twisting wire by hand, and he kept at it until he had rope made of metal. It worked. The orders came in faster than he could fill them on the rope walk at his farm.
By 1848 he understood what he had. He bought 25 acres along the Delaware and Raritan Canal, in the Chambersburg section of Trenton, and by the next year he was manufacturing there. The site was chosen for water, rail, and port, everything a heavy industry needs to get its product out the door. The canal itself is gone now, buried under Route 129.
Through the 1850s and 60s he used his own rope to hang his own bridges: over the Niagara River, over the Allegheny at Pittsburgh, over the Ohio at Cincinnati. Then he turned to the one that would carry his name forever, the Brooklyn Bridge.
He never saw a foot of it built. In 1869, while surveying the location, his foot was crushed by a ferryboat. He was dead ten days later of lockjaw, what we now call tetanus. The bridge passed to his son and assistant, Washington Roebling, who had trained as an engineer at Rensselaer Polytechnic Institute.
When the Roebling sons took over the business from Charles Swan, their father's loyal manager, in the early 1870s, the whole operation was run by 85 men. Ten of them were children under sixteen.
From that, in one lifetime, came all of it. Wire and rope for bridges, for shipping, for two brand new technologies nobody could get enough of: the elevator and the telegraph. In the 1880s, the brothers opened an Electric Wire Division to feed the cities that were wiring themselves for light and sound. In the 1890s came cable cars, which Washington remembered in his memoirs as a prosperous stretch for rope makers. The cars needed longer and longer rope, so Charles designed a machine that weighed eighty tons and could spin a rope 30,000 feet long. Between 1904 and 1914 the plant turned out enormous quantities of wire rope for the tramways and the digging that built the Panama Canal.
The Chambersburg plant ran out of room. In 1902 the brothers built a new one for the electrical division, a mile south along the same canal. By World War I, this was the largest wire rope plant on earth, with 10,000 people working there.
And the wire that came out of these shops went into the North Sea Mine Barrage in the first war, the Bear Mountain Bridge, the George Washington Bridge, and, in the middle of the Great Depression, the Golden Gate. When Trenton put "Trenton Makes, the World Takes" on the side of the Lower Trenton Bridge, this is mostly what it was bragging about.
The family sold to the Colorado Fuel and Iron Company (CF&I) in 1952. CF&I then operated the plant from 1952 to 1974. Trenton operations stopped in 1974, when suppliers overseas with cheaper labor made domestic wire rope a losing proposition.
Eighty-five men and ten children, to 10,000 workers, to nothing. Then fifty years of weather.
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| Humble beginnings of John A. Roebling's Sons Co Rolling Mill in an 1890 map survey. |
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| Flat Shop No.2 |
A Man on a Mattress and Public Shenanigans
Back inside, I moved on to Flat Shop No. 2, and there was nothing left of it but bones. Rusted steel beams, no floors, no stairs, no ladder. I could see a level above me and no way on God's earth to reach it. I stood in a building that had the second flooring removed, for what purpose remains a mystery.
The Annealing House was next, right across from where I'd left my car. I put my head in, and down at the far end, on the left, a man was sitting on a mattress, writing. Head down, working at something. A notebook, a letter, a list, I'll never know. I backed out quietly and left him to it.
So I went into Flat Shop No. 1 instead, the one that fronted the houses on Mott Street. Through the broken windows I could see the ground floor and the middle floor of the row across the way, people's homes, close enough to hear a screen door. I stood still and listened for anything that sounded like someone else's living space. Nothing. I shot the ground floor and went up, where the room opened out again, and from that window I could see that the building I'd just given up on had more floors in it than I'd been able to reach.
On my way out, I checked the Annealing House one more time, half expecting the man to be gone. He wasn't. This time he looked up, and our eyes met, and I turned around and left the way I came.
And then, before I made the corner, I heard branches snapping and rustling.
My heart was already going. I came around expecting anything, and found a man standing in the bushes, pruning a medium-sized tree. Just doing yard work, in the middle of a ruin, on a Tuesday. Of everything I saw that day, that's the image that stayed with me.
Out on the sidewalk, the street had refilled. People moving fast and moving slow, a woman walking behind me who wasn't behind me anymore, and then, a few minutes later, that same woman sitting in the passenger seat of a black Ford pickup as an older man drove her off down the block. I think I know what I watched. I can't swear to it.
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| Mott Street Exterior of Flat Shop No.1 (1905) Photo Courtesy Library of Congress |
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| Ground floor of Flat Shop No. 1 |
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| Second floor of Flat Shop No.1 |
The Final Twist of An Old Building
In the last week of March 2026, Flat Shop No. 1's exterior wall came down on the very sidewalk I walked years earlier.
Not all at once and not because anyone planned it. The building's wall allegedly just collapsed during a freeze and thaw, and once a building begins to do that, there's no argument left to have. It was built in 1905 and rebuilt after a fire in 1912. It stood 121 years. Two World Wars, the Depression, the long slide of American manufacturing, and fifty-two years of rain coming through the roof.
Mayor Reed Gusciora had hoped it could be refurbished. What the city will salvage instead are the stars.
If you've looked at old brick buildings, you've seen them, iron plates shaped like stars, set flat against the wall. They're the visible ends of rods that run through the building and tie the brick walls to the floor beams so the walls can't bow out. They are, in the plainest sense, what was holding the thing together.
Sit with that. John Roebling built an empire out of members in tension, out of steel that does its job by pulling two things toward each other and refusing to let go. And the last thing anyone will take from Flat Shop No. 1 is the iron stars that were doing exactly that until the day the building quit.
Once the lot is clear, the Roebling Complex Redevelopment Area Plan calls for mixed-use and market-rate housing. Across the street, it worked. The old Machine Shop is a museum and a skate park now. A Food Bazaar is doing real business, the offices of the New Jersey Housing and Mortgage Finance Agency, a senior housing community, restaurants people actually drive in for. Trenton knows how to do this. Trenton has done this. Fifty yards away.
And on this side of the street, for half a century, the answer was nothing. Not a plan that failed. Nothing. The collapse in March didn't happen in March. It happened a little bit at a time for fifty-two years, through ignored warnings and deferred decisions and nobody's name on anything, until the building did the only thing left to do and made itself impossible to ignore.
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| Exterior side shot of Flat Shop No. 2 |
Were you or a family member employed at this legendary Trenton wire rope plant — whether under John A. Roebling's Sons Company, CF&I, or any of its iterations? Do you have photographs, employee badges, product samples, or memories of the Flat Shops, the Annealing House, or the Rope Shop? Share your stories as this historic site faces partial demolition and redevelopment.
Source(s):
1. Historic American Engineering Record, C., Roebling, J. A., Roebling, W., Roebling, F., Roebling, C. & Cooper, P. (1968) John A. Roebling's Sons Company & American Steel & Wire Company, South Broad, Clark, Elmer, Mott & Hudson Streets, Trenton, Mercer County, NJ. Mercer County, New Jersey, Trenton, 1968. Benzmitter, trans Documentation Compiled After. [Photograph] Retrieved from the Library of Congress, https://www.loc.gov/item/nj1096/
2. (1890) Sanborn Fire Insurance Map from Trenton, Mercer County, New Jersey. Sanborn Map Company. [Map] Retrieved from the Library of Congress, https://www.loc.gov/item/sanborn05639_001/
3. (1908) Sanborn Fire Insurance Map from Trenton, Mercer County, New Jersey. Sanborn Map Company, Vol. 2. [Map] Retrieved from the Library of Congress, https://www.loc.gov/item/sanborn05639_003/
4. Parker, L. A. (2026, March 1). Wall collapse in Trenton disturbs neighbors on Sunday morning. The Trentonian. https://www.trentonian.com/2026/03/01/wall-collapse-in-trenton-disturbs-neighbors-on-sunday-morning/
5. Loder, S. (2026, March 14). Demolition of historic N.J. building that partially collapsed to cost $620K. NJ.com. https://www.nj.com/mercer/2026/03/demolition-of-historic-nj-building-that-partially-collapsed-to-cost-620k.html
6. Sanborn Map Company. Insurance maps of Trenton, New Jersey, volume two. New York: Sanborn Map Company, 1927. Retrieved from https://maps.princeton.edu/catalog/princeton-47429d054
7. American Society of Mechanical Engineers. (1989, October 21). Roebling 80-ton wire rope machine (circa 1893) [Brochure]. ASME National Historic Mechanical Engineering Landmark. Trenton Roebling Community Development Corporation; DKM Properties Corporation.
8. Hand, S. (1997, April 17). Roebling Machine Shop [National Register of Historic Places nomination form]. National Park Service. https://npgallery.nps.gov/GetAsset/2146fc6b-4d6b-49a7-aeed-e807727938b3
9. U.S. Environmental Protection Agency. (2013, February 12). Roebling Steel Co. site profile. Superfund Site. https://cumulis.epa.gov/supercpad/SiteProfiles/index.cfm?fuseaction=second.cleanup&id=0200439
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