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As many as 800 people flooded Emery's 5 & 10 Friday in Knoxville, Tenn., driving thousands of dollars in business. "It's beyond our imagination," owner Ron Emery said.

Emery's 5 & 10 is believed to be oldest family-owned five-and-dime store in the U.S. But the store is struggling, the victim — like its neighboring businesses — of the economy and a bridge construction project that has diverted traffic away and turned the stretch of Chapman Road in Knoxville, Tenn., into what the mayor himself acknowledges is a "ghost area."

Then came last Friday.

Beginning at 10 a.m., nearly 800 people streamed through the doors at Emery's 5 & 10, ringing up 526 sales — many multiples of the store's usual take. The checkout line wrapped through the store, leaving barely enough room to move, said owner Ron Emery, the third generation of Emerys to tend shop there since the business opened in 1927.

"It's beyond our imagination," Emery said.

It was Knox County Mayor Tim Burchett's doing. Recently, Burchett was watching late-night TV and saw a report on "cash mobs" — flash mobs that organize to drive customers to struggling locally owned businesses — and the light bulb went off. 

"Somebody was doing something at a hardware store in the Northeast, and I just thought: 'Dadgum. We ought to do that right here in Knoxville,'" Burchett said in an interview with NBC station WBIR.

"We need to focus on our small businesses," Burchett said, so "some big-box nationally based corporation" doesn't come in and replace "our mom-and-pop locally owned businesses with a $10-an-hour greeter."

Cash mobs are a very recent phenomenon: The first took place in August at City Wine Merchant in Buffalo, N.Y., organized by Chris Smith, an engineer who also writes for ArtVoice, a Buffalo arts blog.

Since then, the idea has spread to cities like San Diego, where cash mobbers planned to converge Monday night on Fiesta De Reyes, a mall in a state historic park; Warwick, R.I.; Cleveland; Columbia, S.C.; and Austin, Texas. The unofficial rules are laid out on the Cash Mobs blog, which sprang up in Cleveland in November.

"To see our store full of people who are looking and shopping and admiring is fabulous," said Annie Jackson, co-owner of Anything Goes, a gift shop in Warwick where a dozen people were lined up at the cash register during a cash mob last week.

"It's what you dream of when you open your small business," Pam Goes, Jackson's partner in the business, told NBC station WJAR of Providence, R.I.:

"There are a lot of independent local businesses that are having a hard time trying to creatively figure out how to pay the bills," said Tim Hudyncia, a chiropractor who organized the cash mob as part of the Let's Buy Local Business Alliance of Central Rhode Island, which was formed in November.

Rhode Island Lt. Gov. Elizabeth Roberts is backing the campaign.

"A shift in your spending of just 10 percent has the power to create hundreds of jobs and add millions of dollars to Rhode Island's economy," Roberts says in a promotion produced by her office.

The cash mob Monday night in San Diego is the third to have been coordinated by Lauren Way, an HIV researcher at the University of California-San Diego.

While the money helps stores, the mobs are more about changing the way people view local businesses, fostering a culture shift in which consumers are more inclined to shop where their money can make it into the hands of their neighbors, Way told NBC station KNSD of San Diego:

"If one person goes into a local business and spends $20, that's great. That's $20 that went to a local business," Way said. "But if 40 people go into a local business and spend $20, that's $800 that just went to that local business."

Burchett, the mayor of Knox County, said the only drawback to the idea is that some people have a falsely sinister image of flash mobs, a small minority of which have gotten out of hand and driven outsize publicity.

"People get nervous that they're going to take off their clothes," he said. "Of course, that could make a bigger crowd."

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