US-VOTE-REPUBLICANS-TRUMP

Republican presidential candidate Donald Trump speaks at a rally on Sunday in Boca Raton, Florida. Campaign attire, including baseball caps, has become standard fare at political rallies. Many campaign hats are produced at Unionwear in Newark, which has provided hats for several candidates, including Donald Trump last fall. (Getty Images)

At a nondescript factory near Branch Brook Park in Newark, workers have an easy way of gauging the popularity of any given presidential candidate.

As the only unionized American manufacturer of baseball caps, Unionwear has made logo-embroidered hats for candidates of all stripes.

If a candidate is doing well, his or her campaign might put in a large order for hats, said Mitch Cahn, president of Unionwear. Not so well? The campaign might cut back to putting in small orders on a week-by-week basis.

And just which hat has been popular? That would be "Drumpf," the ancestral name of Donald Trump's family, derisively parodied by British comedian John Oliver on HBO, which placed a large order for the hats.

"They put it on their website as a joke and sold way more than they expected," Cahn said.

This small sector of Unionwear's business has cropped up every four years since Al Gore's campaign debuted candidate-themed apparel, Cahn said.

(Unionwear)

"There was really no way before the internet for these campaigns to sell their merchandise," he said. "It's not like they could have traveling stores everywhere they campaigned."

That kind of campaign merchandizing raises money and turns voters into walking billboards - as well as building a connection with voters.

While the candidates differ on many things, they at some point have all ordered Unionwear hats, from Hillary Clinton to Ted Cruz to Trump, briefly.

And their detractors have ordered parody hats as well. Other Trump-related parody hats include "Make Donald Debate Again" and "Make America Gay Again," Cahn said.

Unionwear stumbled into this customer category almost by default. Cahn had made a name for the business selling hats to high-end retailers like Nordstrom and The Gap. However, by the late 90s, almost all garment manufacturing had fled the United States for Asia.

(Unionwear)

The company held on until, lo and behold, they started to get orders simply because they were one of the few American, unionized manufacturers left standing after the brutal purge, Cahn said. Seeing which way the wind was blowing, they changed their name from New Jersey Headware Corp. to Unionwear.

Anyone can order hats, whether it's the official campaign, a political action committee, a union supporting a particular candidate, or state political parties.

Hence the hats Unionwear has made for the non-existent campaigns of Sen. Elizabeth Warren, Vice President Joe Biden, and Speaker of the House Paul Ryan.

Cahn said he's noticed a difference between the orders for Democratic candidates versus Republican ones: The Democrats want to include the "union-made" label, while the Republicans prefer that be left off.

All, however, realize their campaign regalia must be made in America.

Early in the campaign cycle, Trump's now-famous "Make America Great Again" baseball cap came under scrutiny when some said the item was made in China. It wasn't; the cap in question was a knock-off sold online commercially, not by any official party or Trump-connected organization.

(Unionwear)

Trump used Unionwear for about a month last fall, then switched to a California factory, Cahn said. All told, they provided the campaign with more than 20,000 caps.

Although political attire isn't a huge slice of Cahn's business, the spotlight a presidential election puts on American manufacturing drives new business, he said.

"Every presidential campaign cycle there's a news story that a candidate had an item that was made in Bangladesh," Cahn said. "Then companies say to themselves, 'Hey, We should probably look into getting something domestically.'"

Kathleen O'Brien may be reached at kobrien@njadvancemedia.com. Follow her on Twitter @OBrienLedger. Find NJ.com on Facebook.