When Northern Grade hosted its first pop-up marketplace in northeast Minneapolis in 2010, "heritage" style was in the midst of going national.

Minnesota bag manufacturers J.W. Hulme and Duluth Pack — established in 1905 and 1882, respectively — had been picked up by tony department store Barneys New York. Preppy retailer J. Crew had started stocking its shelves with iconic boots from Red Wing Shoes that have been manufactured since 1905. Minnesota's lumberjack look — plaid shirts, selvage-denim jeans and work boots — had gone mainstream.

Five years later, the heritage trend has died down slightly — but Northern Grade, which returns to the Solar Arts Building in northeast Minneapolis next weekend, is still going strong. What started as a Minnesota menswear market has gone on to pop up everywhere from Los Angeles to Moscow, and co-host events with GQ magazine. This November, its creators will open a permanent store in New York City.

Northern Grade was the brainchild of Mark ("Mac") and Katherine McMillan, husband-and-wife entrepreneurs who also founded neckwear brand Pierrepont Hicks in 2009. They envisioned the market as a way to bring Midwest makers of leather goods, canvas bags, boots, gadgets and grooming products together under one roof.

And now, given the opportunity to open a store in Manhattan's burgeoning South Street Seaport district, Northern Grade is set to expand its influence even further. Once the site of chain stores and souvenir shops, the neighborhood is transforming into a shopping district dedicated to unique, independent retailers — thanks in large part to a $10.4 million Federal Emergency Management Agency grant after the area was decimated by Hurricane Sandy in 2012.

Their 3,200-square-foot shop will carry a mix of men's and women's clothing and accessories, home goods and artwork from about 40 brands and artisans, including Minnesota's Tradition Creek, Merchant Leather, Blue Claw Co., Sanborn Canoe Co. and Woodchuck USA.

"The idea is to sell brands and products that either have a minimal or no presence in New York," said Mac McMillan.

Beyond the lumberjack

Mac handles the operations side of the business, while Katherine focuses on sourcing makers for the Northern Grade shop and markets, along with branding and marketing. Although Northern Grade features a consistent roster of brands year after year, the McMillans keep it fresh by continually introducing new ones — many of which Katherine discovers on Instagram.

"You start by following one brand, and that suggests more brands, and then you go down the vortex," Katherine explained. "Before you know it, you have suddenly found a ton of different folks who do the made-in-America thing. It's sort of a happy accident."

Over the years, Northern Grade has broadened its merchandise beyond the Midwest. Next weekend's Minneapolis market features brands such as Austin, Texas-based Noah Marion (leather and home goods) and New York's Krammer & Stoudt (men's clothing) alongside Minnesota names including Woodchuck (wood iPhone and iPad cases), the 2 Bits Man (men's grooming products), Winsome (women's clothing), Leather Works Minnesota and, of course, Red Wing boots.

Like Red Wing, Leather Works has been with the market since its inception. "At the first Northern Grade, Mac put us between Red Wing Shoes and Filson," Leather Works co-owner Lee Begnaud recalled. "Being sandwiched between all of these great big brands over the years has been amazing — we've doubled five times in four years because of Northern Grade."

Although it was originally positioned as a men's market, Northern Grade has since rebranded itself as a "roving American goods marketplace," expanding into women's apparel and footwear as well as original artwork and games. And Northern Grade isn't just about hardy heritage and workwear brands these days. The market's aesthetic has grown to incorporate clean, contemporary design.

"Heritage will always have a place" with Northern Grade, said Katherine, "but there are so many brands and creatives out there doing cool things right now."

Mac added, "We don't want to be typecast into the heritage urban lumberjack thing."

Jahna Peloquin is the style editor of Minnesota Monthly and is a freelance writer and stylist in the Twin Cities.