Flannel 101

“Forty years ago, we were able to make great shirts here, great jeans here, sold at a price that made sense to mainstream consumers,” Mr. Winthrop said at the outset of his project. “We’ve lost that capability in 40 years? We can’t make a flannel shirt in America? I’m not going to accept that answer.”

“Made in America” has become a marketing catchphrase espoused by both Brooklyn $400 selvage denim enthusiasts and Trump isolationists. And brands like American Apparel have led a renaissance of sorts in domestic manufacturing. But producing clothes in the U.S. today is exceedingly complicated. Over the last 30 years, the textile industry has been decimated by outsourcing and unfavorable trade deals, shedding 1.4 million jobs in the process, said Augustine Tantillo, president of the National Council of Textile Organizations.

Communities that produced clothes for generations, like Fort Payne, Ala., the former sock capital of the world, were mortally wounded when mills closed. Sometimes the expertise or work force have dissipated. Sometimes it’s the machinery, the looms, that have gone overseas.

Each time AG develops a new product, Mr. Winthrop must patch together its supply chain from what remains. To help him navigate the process, he relies on “old dogs in the industry,” he said, though AG is based in San Francisco and runs like a tech start-up, with sales almost entirely online.

For flannel, he called James McKinnon.

At 50, Mr. McKinnon is not that old (Mr. Winthrop is 49). But he is the third McKinnon to run Cotswold Industries, the textile manufacturer his grandfather started in 1954. Cotswold made the woven fabric for headliners inside Ford cars. Later, the firm manufactured pocket linings for Lee, Wrangler and Levi jeans. Cotswold still handles pocketing business for many U.S. brands, part of a diverse portfolio that includes making fabrics for culinary apparel. The fabrics are woven at its mill in Central, S.C.

Mr. Winthrop called Mr. McKinnon at his office in midtown Manhattan and ran through the list of questions. Why is flannel gone? What would it take to bring it back? How would you do it?