This year, the hottest event in Chicago for the hip and frugal set was a pop-up flea market born of a blog.

The Vintage Bazaar, a flea market featuring vintage clothing, accessories and furniture, drew 11,000 people to two separate events. The first event, held in February in Chicago’s Lincoln Square neighborhood, drew 3,000 people. The second event, held in August in Chicago’s Logan Square neighborhood, drew 8,000 people.

Vintage Bazaar was organized by two young women with no prior experience running flea markets. Instead, they were driven by a passion for vintage design and social media. The blog Back Garage brought them together.

Back Garage is a blog focused on interior design and secondhand furniture. Katherine Raz, who studied magazine journalism at Columbia College, launched Back Garage in 2008 when she decided to get “a real job.” To demonstrate her skills, her mentor had recommended she start a blog.

“I wanted to combine two things I liked the most, which was shopping secondhand and interior design,” Raz says.

Raz drew on her background in magazine journalism to plan and write her blog posts. To do research, she plowed through books on design and furniture. “I was basically writing magazine-style posts on shopping at estate sales, before-and-after décor pieces, stuff on how to search eBay,” Raz says.

Over time, she developed several features on Back Garage.  One feature was Craigslist round-ups of great furniture finds on Craigslist.

“At the time, there was enough to go around on Cragislist,” she says. “Craigslist has changed a lot in the two years since then because there are so many dealers on Craigslist. In 2009, there were still a lot of people on Craigslist who didn’t know what they had—you could find things really cheap. That’s not so much the case anymore.”

Raz gained a following for creating a weekly round-up of Chicago’s best estate sales and garage sales. She tried to monetize it by charging $1 for a PDF every week. Nine people subscribed. “I was making $9 a week and it was a lot of work to put it together,” she says.

Raz continued creating the list every week as well as doing the round-up. She also began doing  tours of well-decorated homes in Chicago.   A young woman named Libby Alexander contacted her and asked if Raz wanted to do an apartment tour of her place.

While touring Alexander’s apartment, the two women instantly bonded and the conversation turned to flea markets. Raz had been inspired by Chicago’s Renegade Craft Fair, a fair featuring handmade goods. “I’d done a post on how people had used vintage display pieces in their Renegade set-up, like using an old vintage cake dish to show whatever handmade thing they were selling,” she recalls. “I was thinking, I wish there was something just like this but for vintage things.”

Alexander and Raz put their heads together, trying to think of a flea market in Chicago that focused on design and vintage items. They couldn’t think of one.  That’s when they got the idea to do it themselves.

“We thought we’d do something small, at the Empty Bottle [a small concert venue in Chicago],” Raz says. “I’d contacted Colleen, the Chicago community manager at Yelp, and asked her where I’d do this.  I’d obviously never done an event like this before.”

The Yelp community manager connected Raz and  Alexander with Dank Haus, which is also the German American Cultural Center in Chicago. A ballroom is on the fifth floor of the Dank Haus. “I remember walking into the ballroom and thinking, ‘This is huge—she’s out of her mind,’” Raz says. “But Colleen kept saying if you’re going to do it, you should it big.”

Raz used Back Garage to advertise that she was looking for vendors to sign on for the flea market. Alexander and Raz also scoured Etsy, the e-commerce site for handmade goods, to find people who’d never considered selling at a flea market.  All in all, 40 vendors signed on.

The day of the event, Raz and Alexander had no idea what to expect. The 40 vendors sold a mix of goods—vintage clothing, handbags, jewelry, 80s memorabilia, vintage glasses, household décor, repurposed vintage accessories and furniture.

More than 3,000 people showed up that day at Dank Haus. It was way more than Raz and Alexander had expected, especially considering the ballroom is on the fifth floor of Dank House and furniture would need to be carried out. In fact, the crowds were so big, Raz and Alexander had to do crowd control.

“The vendors were so buzzed—everyone had a good time,” Raz says. “It was pretty obvious that we needed to do it again.”

Raz and Alexander scouted Chicago for the right next location. They found it in the Congress Theater, located in Chicago’s Logan Square neighborhood. Held in August, the second Vintage Bazaar drew almost three times as many people. More than 8,000 people packed the Vintage Bazaar that day.

Raz credits the success of the second event to social media. “We selected vendors for event who already had a blog or a website, who were selling online, who were on Twitter or who had a Facebook page for their shops,” Raz says. “They were also mouth pieces for the event, which I think is really key.”

Raz now works full-time on Vintage Bazaar and Back Garage, which she turned into an online shop for refurbished furniture. “I go to estate sales, auctions, flea markets where I buy furniture and clean it up,” she says. “I have a garage that’s already overflowing and am trying to find a space in the city that I can use as studio to refurbish stuff and list online.”

You could call it an ironic twist of fate, considering Raz launched Back Garage in 2008 as a launching pad to a “real job.”  Really it speaks to the power of social media and Raz—and Alexander’s—ability to harness it into a real-life community of people who are passionate about all things vintage.