Between the I-95 highway and the placid New Haven Harbor waters, 35 flags continually beat back and forth, defying their otherwise colorless urban surroundings.

The flags are Bill Shields’s and he has many more to offer — 600 types, at least. Known as the “Flag Man of Long Wharf Drive,” the merchant has advertised his colorful products within sight of the I-95, tethering them to his small, white van. The spot along Long Wharf Drive is perfect, he said, because the wind and the highway comprise his “publicity agent.”

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“Madison Avenue couldn’t get me more attention,” he said, chuckling at the prospect.

Within the old food service van that now serves as his store, Shields sits with three and a half feet of elbow room, doing a sudoku puzzle. Brimming with folded flags, stickers and military pins, the vehicle evokes a sense of seclusion uncommon in 2007 — Shields has no office phone or Web site, and protects himself from cold weather by sitting next to a heater attached to a fuel tank.

Customers either find him through word of mouth or when they happen to catch sight of his multicultural clothesline of fabric flags, which sport anything from smiley faces to Budweiser logos to the American flag. Shields said he parks the van around 10:00 a.m. every day, opens shop at 11:00 a.m. and departs around 5:30 p.m., except on Mondays, which he takes off. More intuitively, he “goes by the sun,” refraining from work if the temperature is less than 30 degrees Fahrenheit.

“It’s a strange business, but I like it,” Shields said. “It’s a niche.”

Ask Shields for any flag, and he will not only have it in stock, but he can find it without reading the flag tags. Then he’ll explain the flag’s colors and symbols, or relate a story a customer once told him about the flag’s history.

Pulling out a gaudy dark green fabric with a light blue block of stars at its corner, Shields’ voice suddenly thawed, as if reliving a memory of a man he met yesterday. The flag, he explained, was designed by Revolutionary War fighter Ethan Allen.

“It’s quite ugly, isn’t it?” Shields said. “The guy was a maniac, an absolute, drunk maniac! He was basically an insurgent.”

For Shields, the aesthetic appeal of flags amounts to very little when compared to their complex histories. Researching flag records in his leisure time, he carries traditional flags as well as flags sporting collegiate and athletic logos. In addition to his collection of over 20 historical American flags — which often do not display the traditional red, white and blue — Shields markets dozens of flag replicas from in American history: George Washington’s personal flag, a long-defunct Russian-American fur company flag and the ever-popular black-and-white P.O.W. flag.

“People love to keep in touch with the past,” Shields said. “It’s just an aspect of human nature. You can see where you’re going if you know where you’ve been. I’m a firm believer in history repeating itself.”

Shields said the van receives 10 to 15 customers on a typical day, but more if the weather is tame. An hour before closing time, fourth-grade teacher Betsy McKenna walked over, looking for a teaching prop.

“This is going to sound really weird, but do you have the international flag of Spain?” she asked.

The merchant hardly batted an eye. “Sure I do. The traditional one? I have it in three by five, five by seventeen, twelve by eighteen.”

Flag customers often come searching for reminders of home, Shields said, or they want flags in the wake of global competitions or controversies.

“Competition can be the [FIFA] World Cup, or it can be when things heat up between one nation and another,” he said. “Whenever Israel gets in the news because of a conflict in the Middle East, I’ll get requests for flags, like I did last summer. I don’t carry Hamas flags, but I do have Palestinian flags.”

But to run the best flag business, it’s not enough to sell just one side’s flag or the emblems of all the warring nations, he said.

“You have controversy, and you profit from both sides,” he said. “[But] a good flag man always carries a flag with a peace sign on it, too.”