To those who live on the coasts, Chicago may long have been considered fly-over country even when it came to fashion. The past decade has turned much of that dismissive attitude on its ear—thanks to high style guru Ikram Goldman opening her boutique here. (Her semi-secret styling of the First Lady for the past three years hasn't hurt, either.) The also fashionable boutiques of June Blaker, Blake, and Chalk have helped ratchet up Chicago's style profile.

Now, for one day at least, Chicago style will be front and center in the fashionista world. A personal treasure trove of 140 items designed by Norman Norell, a quintessential American designer, will be auctioned online on October 19 on 1st Dibs. All of these items come from the collection of Beverly Dowis Blettner, a Chicagoan socialite and philanthropist. Around town, Blettner was known for years as a very chic woman who might try to literally talk you out of the clothes on your back. As president of the Costume Committee for the Chicago Historical Society (now the Chicago History Museum), Blettner, now 78 and housebound, was famous for accosting women at social gatherings and asking them to donate what they were wearing to the Society's collection. She was also well-known for rooting through her friends' closets for stellar items that could go to the Society.

Then someone finally looked in Blettner's closet. "Actually, she kept her Norells in a separate apartment," says Ricky Serbin, a San Francisco-based vintage clothing dealer. "They were kind of enshrined." Serbin first heard about Blettner's collection of Norells through a mutual friend. Then he began a long process of convincing Blettner to put the items up for sale. "It was hard for her and I get it," he says. "It's a real collection. And she had worn every single item; she even had some duplicates of particularly favorite styles. She obviously loves them."

Timing played a big part. The clean, sophisticated lines of Norell can be seen in so much of today's fashion. "Guicci, Vuitton, Burberry—they are all showing fall and winter coats done in retro-style heavy wool," says Serbin. "I mean, these Norells look like they walked off a Fall 2011 Runway." Indeed. There are color block dresses, capes, shirtwaist dresses, Norell's signature bow blouses, and military-style coats. All were designed by Norell between 1960 and 1972 (his last season); many are in mint condition. And when Michelle Obama wore a vintage Norell last December—becoming the first First Lady to ever wear vintage fashion—the notion of wearing vintage Norells became very chic.

Or so Serbin hopes. "Traditionally, Norell designs have been underappreciated," he says. "But when you see these Burberry or Gucci coats of the same style selling for $6000, and you can own an original Norell coat for $1700, why wouldn't someone buy?" In general, the prices for Blettner's clothes will range from $200 for a patent leather belt to $4900 for a cape coat. Colorblock dresses will average $950 and those winter coats—all lined with taffeta—will cost $1700.

One thing missing from the Norell sale will be any of his famous mermaid dresses. Blettner gave hers to the Chicago Historical Society years ago.

Photographs: 1st Dibs