SOUTHOLD, N.Y. — The American flag flies in paint on the side of Peter Treiber Jr.’s potato truck, a local landmark parked permanently on County Route 48, doing little more, he thought, than drawing attention to his family’s farm.

Until he tried to sell his produce.

At a local greenmarket where he sells things like wild bergamot, honey and sunflowers, he had trouble striking a deal until, he said, he let his liberal leanings slip out in conversation with a customer.

“She said, ‘Oh, whew. You know, I wasn’t so sure about you, I thought you were some flag-waving something-or-other,’” Mr. Treiber, 32, recalled the woman saying and citing his potato truck display. “That’s why she was apprehensive of interacting with me.”

He paused: “It was a little sad to me. It shows the dichotomy of the country that a flag can mean that. That I had to think, ‘Do I need to reconsider having that out there?’”

Thirteen stripes, a dusting of stars, the American flag has had infinite meanings over the 244 years since the country began flying one. Raised at Iwo Jima, it was a symbol of victory. Lit on fire, it became a searing image of the protests against the Vietnam War. Ribboned around the twin towers on commemorative Sept. 11 lapel pins, it is a reminder of the threats against a delicate democracy.