The overalls — one of the hundred or so pair that flank the retail space at Hudson’s Hill in downtown Greensboro — have seen better days.

They’re Blue Bells, made in a plant in Greensboro right around 1940 from heavyweight Deeptone denim, woven exclusively at Cone Denim’s White Oak Mill. When they were new, they were stiff as stovepipes. Deeptone denim, introduced in 1936, was a smoother weave than its predecessors in the denim industry, but still it was made to endure hard work. Sweat and friction have worn this pair down to linen.

Though the overalls hang just a few miles from their place of origin on Summit Avenue, the road has been a rough one. A chain of hand-sewn patches runs down the right leg, from hip to shin. More patches, these in a faded mosaic of stitchery, reinforce the left knee. The pockets on the bib show signs of heavy use. In some spots, the indigo dye has faded to white.

Evan Morrison, proprietor of Hudson’s Hill, reads the overalls like a document.

He points to the knees.

“See how they’re not just a single patch, but a patch on a patch?” he says. “What does that tell you? This guy had a job that was heavy on the knees.”

Either a mechanic or a fieldhand, he says.

“Now look again. I see very few oil marks, meaning they probably didn’t use machines. There’s heavy sun fade. Look at the patch on the inside of the knee.”

The bib is telling, too.

Like all overalls of the day, Blue Bell installed a buttonhole at the top center of the bib to accommodate a pocket-watch chain. Some of the vintage overalls hanging from his wall show a circular fade pattern where the watches hung. This particular pair shows no such marking.

Morrison begins to fit the overalls with their original owner using details from his pants.

“It’s probably someone who doesn’t have a lot of money,” he says. “You had to get a pocket watch from like the Sears catalog. They were expensive.”

He notes heavy use in the bib pocket, for a wallet or maybe tobacco. And there’s a fade in the slim bib pocket made to fit a writing instrument.

“He probably carried a pencil,” Morrison says, but notes that the fade is not as prominent as others on the pair. “He could have been a farmer who sometimes went to market and had to write things down.”

The owner of these pants probably wore them every day, Morrison says.

“Back then, getting dressed up was like throwing on a suit jacket over your work clothes.”

Morrison collects salvaged denim clothing like some people collect books. But he sells the new stuff, too: high-end dungarees built to endure decades of wear, with selvage stitching at the seams and solid riveting at the joints, sewn from raw denim that, like the pants it informs, must be built the old-fashioned way. Modern machinery cannot replicate the denim that our grandfathers wore. The kind of denim that brings a price point into the three figures is made on a vintage fly-shuttle loom. And the only place that still uses them is the White Oak Mill.

The Draper fly-shuttle loom is 3,500 pounds of iron and wood, levers and gears, pulleys and springs, a machine in the truest sense. It weaves a strand of white cotton thread from a spinning magazine — the fly-shuttle —between triple threads of indigo. Inferior denims weave two to one; lighter fabrics like chambray and sailcloth cross the threads in the weave at a one-to-one ratio.

In its heyday in the late 1940s, the White Oak Plant in Greensboro had 3,152 of these looms rolling out 125 million yards of Deeptone denim that made clothes for farmers, miners, soldiers, mechanics, cowboys and everyone else that did an honest day’s work. Even prisoners wore denim. A lot of them still do.

But as denim clothing became more about form than function and competition from overseas mills drew away market share, the Cone empire went into decline. The Proximity Printworks shut down in the late 1970s. Revolution Mill followed in 1983. The Cone Mills Corp. filed for bankruptcy in 2003, its assets merged into International Textile group.

And so it went, until new fashions and vintage style conspired to create a new demand for an old product.

The old shuttle looms made a tightly woven fabric a yard wide with a sewn edge, or “selvedge,” to prevent fraying. Modern projectile looms make much wider swaths of fabric, but not as tightly woven, and the edges are left to fray. Only the industrial-era machines could make denim the old-fashioned way.

In 2012, the White Oak plant reinstated a few hundred of the old machines to meet the demand of denim connoisseurs. It’s tough to get inside the oldest continually running denim plant in the country. But there’s a loom on display at the Greensboro Historical Museum, on the third floor. It looks like a steampunk table monster.

White Oak was one of two mills built by Moses and Ceasar Cone during the great industrial age. The mercantile brothers came down to the New South late in the 19th Century and found advantage in Greensboro, where the cotton met the rail lines that brought it to the world. The Cone brothers made their first way station in the chain of commerce, the Proximity plant, in 1896. Revolution Mill, for flannel and chambray, came on in 1899 and was acquired by Cone in 1945. White Oak dates to 1905, built strictly for denim. It is perhaps the most consistent manufacturing hub in the city.

A piece of company literature from 1925 describes the symphony of the machines in poetic language: “Each machine sings its own individual song, all merging into an anthem that bespeaks untiring force, directed by indomitable will. So it goes until the hour of shutting down, when falls a silence so deep, so sudden, it seems that, with a last exhausted gasp, the giant has dropped off into a death-like sleep to recoup for tomorrow’s toil.”

The sprawl of the White Oak mill exists behind barbed wire at the junction of Summit Avenue and 16th Street, along North Buffalo Creek. Three tall stacks poke into the sky, and steam chuffs from two rooftop ports. The structure itself is made from massive chambers grafted onto one another through the decades — Industrial Revolution meets sawtooth meets art deco — and an acre of asphalt holds more than 50 truck trailers emblazoned with the pinecone logo.

You can see the old Proximity Printworks across the creek from White Oak: an industrial graveyard taken over by kudzu, broken glass and graffiti. The railroad spur ran right through Proximity to pick up cotton and drop off printed textiles. An elevated section of track still runs through the plant, with sizable trees growing between the crossties.

The third corner of the triangle, Revolution Mills, once churned out miles of that other fabric essential to the wardrobe of the working American: flannel. The mill, with a million square feet over 14 acres, sat mostly dormant for decades before being purchased by Durham’s Self Help nonprofit for $8 million in 2012. Now, scrubbed brick and new windows mark the façade, the water tower painted a cheery red. An event space at the rear accommodates weddings and reunions, and a list of businesses fill spacious and light office suites carved within the skeleton of the old mill’s structures: attorneys, salons, community organizations, a Spring Garden Bakery among them.

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Denim is built to work; the heavy stitching and reinforced joints of the original product reflect the many trials to which it was exposed: fire and sweat, machine and bramble, steel and brick, leather and horseflesh. The high-grade denim carries indigo warp threads across a vertical plane and white cotton through the horizontal, interlaced in good denim at a ration of three blue threads to one white. There is some variation: Inferior weaves go two to one; brown thread can be substituted for the white or the blue; a pinstripe can be introduced; all manner of dyes can be applied. But all denim clothing has the same DNA.

It’s unique in its durability, and also because of its fading patterns, which vary according to stress points, sun and rain exposure, task demands and even, as Morrison’s overalls demonstrate, the individual work habits of the wearer.

Denim makes for a highly personalized garment, uniquely American, with an instantly recognizable backstory deeply ingrained in the American consciousness.

Bikers and greasers appropriated jeans as an expression of rebellion by the 1950s, which began a 10-year cycle of denim fashion trends. Faded denim blew out into bell bottoms and wore personalized patches and embroidery in the 1960s, which lasted into the 1970s, when punk rockers cropped and sliced their jeans just as suburban moms and disco divas slid into skinny designer denim fashions. The ’80s had acid-wash and tactical fraying. The 1990s must bear responsibility for the trend of oversized baggy jeans — and the bell-bottom resurgence — just as the aughts can take credit for the low-rise waist and skinny-jean cut.

Now the market’s demands are at full circle. Cone’s got the old machines out at White Oak making the three-to-one twill and it’s being cut, shaped and triple-stitched into garments that should last as long as the ones hanging from the wall in Morrison’s downtown shop.

Denim pinstripe coveralls from the 1940s have hand-stitching on the pocket and pop burns on the lap.