In Corvallis, Oregon, a couple miles north of the Oregon State University campus, sits a WinCo Foods discount supermarket and, unless you’re in need of groceries, you might drive by without noticing it. I assure you, however, it’s an extraordinary building, a laboratory of capitalism worthy of pilgrimages by the world’s great business schools.

It is not the fact that the building itself is not well presented. With an enticing glass storefront similar to the designs you might see completed by the INDUSTRIAL DOOR COMPANY, and familiar signage adorning the walls, the building is immaculately well kept. However, it is the astonishing wealth hidden away in the bank accounts of the occupiers of this building that is something of a well-kept secret.

Inside the store labor 130 employees of WinCo – grocery clerks, shelf stockers, display builders, bakery workers – and their combined retirement savings roughly comes to an astounding $100 million. And that figure is growing rapidly, such that in a few years the average wealth of these employees could easily exceed $1 million. Quite a few individual workers already have account balances above that level.

Outside of Wall Street and Silicon Valley, the WinCo store represents an unusually concentrated – and unlikely — grouping of millionaires. The secret to their wealth is employee ownership. Since 1985, WinCo, which operates 98 stores across eight states from its headquarters in Boise, Idaho, has been employee owned, with an Employee Stock Ownership Plan, or ESOP, as the vehicle for its workers’ main retirement savings. (WinCo also has a 401k and about 70% of workers participate.)

The company is by all indications well managed, grows steadily and provides its clientele of families on a budget a combination of low prices, wide selection and efficient and friendly service. Sales for fiscal 2015 are expected at about $6 billion. Same store sales growth and expansion into new markets have propelled WinCo’s profits and thus its ESOP stock past competitors and, indeed, past most growth stocks. The shares have risen at a compounded annual rate of about 20% since 1986. Purchased for $10 million from its former owners in 1985, company workers today hold shares valued at close to $3 billion.

The Corvallis store, with a long-tenured staff, leads all other WinCo stores in accumulated wealth. But it’s hardly an outlier: workers at a Lancaster, Calif., store have piled up more than $75 million; Redding, Calif., more than $65 million; Twin Falls, Idaho, more than $54 million; and those who work at the company’s distribution centers have combined ESOP accounts valued at more than $165 million.

In Corvallis, the story of Cathy Burch and of her twin sister, Deborah Cook, explains not only the WinCo miracle but also much about the retirement savings crisis in the U.S. On the same day 23 years ago, Cathy and Deborah, then aged 19, walked into the WinCo store and applied for jobs. Each of the women was already a young mother and they were looking for steady work to provide for their families. Retirement savings weren’t on their radar screens.

WinCo at the time had an anti-nepotism policy and could only hire one sister; Cathy scored slightly higher on an employment test and joined part-time, working two days a week, which she fit in around a 40-hour schedule at a fast food outlet. After a year flipping burgers, Cathy received a 5-cent hourly raise and was offended by the smallness of the sum. She quit and went full-time at WinCo. In the years since, Cathy has worked a variety of front-line jobs at WinCo, including checker, shelf stocker, inventory orderer and, when I spoke to her one recent morning at about 4:30 a.m., she was headed off to do “go-backs” for the day, restocking items that customers put into their carts but later choose not to buy.

These aren’t tasks we normally associate with robust retirement savings, and the Employee Benefit Research Institute would tell you that most Americans in Cathy’s situation have either no savings at all or an account such as a 401k containing less than $50,000.

Cathy tells me, while getting ready for work, “I have almost $1 million in stock.” She’s 42. “If I wanted to, I could retire right now,” she adds. Instead, she plans to work a good deal longer, perhaps another 15 years, to fund a comfortable retirement for herself and her husband, Kevin, and also to help their five children, ages 13 to 27, get a good start in life.

“This is the chance of a lifetime,” Cathy tells me. “The work is hard. But it’s consistent. I’m used to it. When people quit WinCo, I ask them, ‘Are you crazy?’ ”

Now let’s check back in with sister Deborah, who generously agreed to share her story with me. Deborah, too, has worked hard at jobs, moving north to Portland: three years at the regional telephone company; some time at a department store and at a pharmacy; finally at a doctor’s office for 17 years. By 2008, Deborah, quite typical for someone in her position, had about $30,000 in a retirement account, and it was mostly in stocks. The market collapse roughly cut that total in half, and that was a wake-up call. “Since then, I’ve been looking for another career,” Deborah tells me. “Even if I had to go to lower pay but better retirement, I’d do it.”

After three years of applying, she recently landed a job with a federal agency and figures, after working 25 years until age 67 she’ll have a decent pension: “I’m 42. I had to start over.” For working Americans, of course, a secure and adequate retirement income is increasingly rare and difficult to obtain.

WinCo is one of thousands of ESOP-owned U.S. companies employing millions of workers. And its industry includes many employee-owned chains, including Publix, the largest employee-owned company and another great example of capitalism played as a team sport.

WinCo has more than 400 front line employees with more than $1 million in their ESOP accounts and hundreds of retirees similarly well set. Each year, it sets aside an amount equal to about 20% of each employee’s pay, in the form of stock, and the value of the underlying shares has risen rapidly, too. Retirees can cash out their shares and in fiscal 2015, ending early next year, WinCo will have paid out approximately $200 million to retirees. Over the last seven years, it has paid out almost $1 billion to retirees. Retirees pay the usual federal and state income taxes on these payouts.

Operating as an S-Corporation for the past decade, WinCo doesn’t pay federal or most state income taxes. As a pass-through vehicle, the owners pay the full complement of income taxes when they retire or otherwise withdraw their shares. The tax benefit has allowed the company to expand by investing heavily in new stores.

WinCo competes directly with Wal-Mart (WMT) and other discount grocers, keeping its costs low. It doesn’t accept credit cards. Customers bag their own groceries. It scarcely advertises. And that efficient approach permeates the workplace, where, as at other ESOP-owned companies, there is a self-policing culture among workers that reduces waste and boosts productivity. “We work our tails off,” says Lance Hart, another Corvallis store employee with 28 years at WinCo. “We’re more of a team than just working for a typical company. There’s a carrot out there you’re working for, for the rest of your life.”

WinCo management was nice enough to confirm historical and financial facts in this article, but preferred to let front-line workers such as Cathy Burch and Lance Hart speak for their colleagues.

WinCo is an unusual workplace. But the power of employee ownership – to transform a company’s culture and to reward hard work with financial security – is available to most American companies. Together, the productivity advantage and the significant tax benefits make an ESOP an attractive exit strategy for most any owner, including private equity funds. One of the great bonuses of working around employee-owned companies, as I have for more than 25 years, is meeting people like Cathy Burch and Lance Hart, who’re enjoying well-deserved success.