It's has nowhere near the name recognition of Black Friday, but Small Business Saturday could have a much bigger impact on retail sales and the economy. Many local businesses are hoping American Express (AXP -0.08%) can get consumers to buy into it and make at least one Christmas purchase in their stores this weekend.

Like Cyber Monday, Small Business Saturday is really a made-up "holiday." But where the online version was concocted by the National Retail Federation's Shop.org division to extend the Christmas shopping extravaganza from the big box stores to their e-commerce storefronts, the newest but little-known shopping event has a more noble purpose: saving local independent businesses.

The idea started with a blog post some five years ago by the Canadian consulting editor of BizWomen.com, musing about the implications of consumers spending just $50 a month in their local community. A blogger figured that if just half the employed population in the U.S. spent that amount locally, it would generate $42.6 billion in revenue. 

From that post, the 3/50 Project was launched to encourage consumers to spend $50 in three local businesses they couldn't do without and watch the economic benefits flow.

Big returns are possible by shopping at small, independent businesses. Source: Facebook via Small Business Saturday.

According to the site, for every $100 spent at an independent retailer, $68 of it goes back into the community through things like taxes and payroll. Spend it at a big, national chain, and only $43 returns to the community. And if you buy into the Cyber Monday phenomenon, nothing is returned locally.

American Express saw the opportunity to help small businesses (and, no doubt, itself) and began sponsoring the event in 2010. The credit card giant has a long history of helping local businesses, and its Open channel is its official portal for doing so. It is promoting the new shopping holiday on a dedicated website as well as across all social media.

On Saturday, if AmEx card members spend at least $10 at participating local businesses, they can get $10 back, up to a total of $30.

Retailers are still looking to ring the bell with higher Christmas sales this year. Source: National Retail Federation. 

The National Retail Federation said it expects Christmas sales over November and December to rise 4.1% to $616.9 billion from 2013's total. But Shop.org estimates online sales will surge even higher, rising 11% over last year to $105 billion. That kind of market muscle is tough for small businesses to compete with.

For example, Wal-Mart (WMT -0.65%) straddles both the physical retail world and the e-commerce plane. Not only is it the biggest U.S. retailer, but its website is one of the most heavily trafficked sites on the Internet around the holidays. With 250 million visits last year, it is second only to Amazon.com (AMZN -1.14%), which had 903 million visits.

Wal-Mart is raising the stakes again this year by making Black Friday a five-day event. And like many other national chains, it's opening on Thanksgiving Day to capture as many sales as possible. Although by doing so, retailers merely pull sales forward from Friday (and the rest of the weekend), they feel the need to do it because their rivals are doing it.

According to Businessweek, U.S. consumers aware of Small Business Saturday spent $5.7 billion in local businesses last year. That's not pocket change, but it's not going to make much of a dent in the armor of the big box stores or the online giants. However, it may just give independent shops enough of a tailwind to keep them going for another year.