On an afternoon in September, in a 70,000-square-foot factory in New Jersey, the brims of thousands of camouflage hats were being steamed into a gentle bend so they could be boxed up and shipped across the country.

A large digital display that usually keeps track of how many hats are produced throughout the day had been turned off, because these hats — official merchandise for the Harris-Walz campaign — had been moving down the assembly lines too quickly to count.

“I’ve never seen a surge like this,” said Mitch Cahn, the president of the company, as he walked through the labyrinthine space, where samples and patterns for different bags and caps hang from the ceiling.

Cahn had been surprised by the popularity of the hats: After Vice President Kamala Harris announced Gov. Tim Walz of Minnesota as her running mate in August, the campaign sold over 50,000 in just a few days. But he hadn’t been caught totally flat-footed.

For more than three decades, Unionwear has been responsible for the merchandise of major presidential campaigns on both sides of the aisle — including for both the John McCain and Barack Obama campaigns in 2008 and for Donald Trump’s 2016 campaign, when the former president introduced the original MAGA hat. Cahn still fulfills orders for the unmistakable red hat from third-party groups.

Unionwear started making political hats during the 1996 Clinton campaign, but Cahn said it was the 2000 Gore campaign that started to put merch — and, by extension, where it was made — center stage.

Part of what campaigns are buying is the “Made in USA” label, which has become increasingly coveted by consumers and brands alike in the past few decades. It’s why companies like Ford and Budweiser, as well as the U.S. Army and Coast Guard, have their merchandise produced in this New Jersey factory.

On the Harris-Walz hats, an American flag tab is prominently featured on the back strap, and in the campaign’s web store the product description reads “American made, union made.”

While there are no laws against making campaign merchandise overseas, Cahn said, “whenever a candidate buys merch that’s not ‘Made in USA,’ it is in the news.”

Cahn, a New Jersey native, came to hat making in a roundabout fashion. After spending his college years at the Wharton School preparing for a career in finance, he lasted only two years on Wall Street before he found himself itching to get out. When he heard a union-run hat manufacturer in Jersey City had gone bankrupt and was selling its equipment, his ears perked up. He knew he wanted to keep the shop union, he said, and hasn’t looked back.

“We were union from Day 1, and that was intentional,” Cahn, 57, said. “I didn’t even know how to manufacture hats. The workers did. You could still see now when you walk around, the place runs itself. There’s just a lot of know-how.”

Since Cahn bought the business in 1992, the company has grown to 165 workers from just six, and moved to a large factory building in Newark, nestled among residential buildings and a baseball field.

To prepare for the election season, Cahn makes sure all 165 workers are familiar with hat production and shifts around other contracts to account for election merch surges. At first, they didn’t see many orders coming in for the 2024 race.

“We saw virtually no Biden sales all year,” he said.

But when Harris became the nominee and Walz joined the ticket, enthusiasm for their campaign — and for the style of hat that came to be associated with it — led to a huge increase in Unionwear’s production.

The factory usually produces 2,500 hats a day, maxing out at around 4,000. Lately, Cahn said, it’s churning out about 5,000 Harris-Walz hats a day.

That may be partly because baseball caps, while timeless, seem to be in the middle of a fashion moment. Harling Ross Anton, the writer behind the fashion Substack Gumshoe, says it’s the result of the “continued trend-ification of merch.”

The simple baseball cap has been near the center of several trends of late, including “quiet luxury” and the men of fashion week sporting shredded caps en masse. Ross Anton also pointed to recent runway shows like Bally’s spring 2024 collection, which featured models sporting soft dad hats paired with skirts, silk blouses, slacks and trench coats.

“It’s rare for any merch to be good,” Ross Anton said. What matters, she added, is “whether it is capable of standing alone from a design perspective, regardless of its brand affiliation.”

In that respect, the camouflage pattern of the Harris-Walz hat may have also helped boost it to mega-popularity. Photorealistic camouflage has become increasingly trendy among young people in the hipper corners of American cities and continues to be a stalwart in more rural parts of the country.

Part of what makes caps so popular, now and always, is their versatility. They can signal status, taste, political allegiance, solidarity, brand loyalty or simply which team you are rooting for — usually operating on multiple levels at once. It is a simple, cheap article of clothing that can let the world know where you stand.

At around 1 p.m., some of the workers at Unionwear were starting to clear out of the break room and return to their sewing, embroidery, eyelet and other machines that together help make the 23 different parts of a baseball hat.

It all starts in the cutting room, where bolts of fabric are laid out in tall stacks before being cut by a computerized machine. The panels of the crown are then sewn together. Unlike buying blank ball caps and having them embroidered, Unionwear embroiders the panels of the hat before they are stitched together on large machines that sew more than a dozen panels at a time.

While the machines hummed, Cahn reflected on a correlation that he has noticed over the years when it comes to presidential campaigns and the hats they make.

Since 2008, he said, the number of hats ordered by a presidential campaign has foretold the winner of that year’s election.

In 2016, Cahn said, the Hillary Clinton campaign hadn’t moved many baseball hats.

“That was fascinating to us because she did not sell any hats,” Cahn said. “We were just trying to reconcile that with the presumption that she was going to win.”