SIOUX FALLS, S.D. — Lewis Drugs, one of America’s most successfully innovative drug chains, is celebrating its 70th anniversary.

The first Lewis drug store — the first self-service drug store to open its doors in the Upper Midwest — rang up its first sale in February 1942 in downtown Sioux Falls. Today, 32 drug stores in three Prairie states carry the Lewis banner, combining to generate annual sales in excess of $150 million. Equally impressive, the drug chain has entered its third generation of family ownership and management.

Lewis is impressive on many levels. For one, it is the dominant drug chain — and one of the major retailers — in South Dakota, a state that offers consumers the considerable presence of Walgreens, Walmart and Hy-Vee, the leading grocery chain in the Midwest.

For another, though 22 of Lewis’ stores can be classified as traditional drug stores, 10 cannot. Those 10 average over 40,000 square feet, and they successfully sell, in addition to the standard drug store product assortment, all manner of general merchandise, from food, wine and liquor to an outdoor living mix that often includes extensive assortments of horticulture products, sold from a greenhouse adjacent to the store.

As for the other 22 Lewis stores, they include 18 traditional drug stores, two clinical pharmacies and two long-term care pharmacies.

Then, too, Lewis has developed a close relationship with South Dakota’s leading medical group, Sanford Health, which has partnered with Lewis to provide Sanford patients with prescription drugs and other drug store-delivered health care services. Indeed, the Lewis-Sanford alliance is among the most progressive partnerships yet formed by a U.S. drug chain.

But perhaps the element that most dramatically sets Lewis apart from most other U.S. drug chains is the longevity, consistency and quality of its management. The company is led today by 30-year Lewis veteran Mark Griffin, who began his Lewis career in 1978 as vice president of inventory control. Mark is the son of John Griffin, who founded the company 70 years ago, after apprenticing in the drug store business with O.P. Skaggs, one of six legendary Skaggs brothers who collectively exerted a stronger and more permanent influence on retailing in America and the way it has developed and prospered than any family in the industry’s history.

Griffin has surrounded himself with a cadre of homegrown senior managers who collectively run the company and make all major decisions — with the exception of those that Griffin, as president and chief executive officer, has reserved for himself. Apparently, however, this will not go on indefinitely. Griffin has already brought on board the company’s third generation of family managers: Nikki Griffin, Mark’s daughter, who is currently Lewis’ corporate counsel and is in the process of learning all facets of the business.

Two other elements set Lewis apart. For one, Mark Griffin has emerged as one of the leading figures in chain drug retailing, a visionary whose opinions are eagerly sought and closely considered by the board of directors of the National Association of Chain Drug Stores, on which he sits. Indeed, rarely in the industry’s history has the head of a regional drug chain risen to command the respect in which Griffin is held. But he comes by his reputation honestly, having served as an NACDS board member since 1997, and as the association’s chairman in 2002 and 2003.

At the same time, Lewis’ CEO has justly earned a reputation in his home state as a thought leader in both the business and health care communities. As one of the larger employers in South Dakota — Lewis employs about 1,000 workers — Griffin is routinely included in discussions of the state’s economic issues. As head of the state’s leading community pharmacy retailer — Lewis’ annual prescription drug volume is some $110 million — Griffin is accurately viewed as an authority on health care in South Dakota — and beyond.

Withal, it is the stores that constitute Griffin’s most impressive accomplishment. Rare is the resident of eastern South Dakota who doesn’t routinely shop a Lewis drug store for prescriptions and basic health and beauty products — and much more.

Indeed, the retailer’s 40,000-square-foot stores can more accurately be described as general merchandise emporiums than drug stores, offering a range of merchandise more suited to a Walmart discount store than a conventional drug store. Products the retailer sells on an everyday basis include name brand outdoor grills with retail prices that often exceed $500; high-end outdoor furniture sets; a variety of plants (kept fresh, by the way, by some of the most modern and innovative cooling and lighting systems in use anywhere) and garden supplies and accessories to rival any in town; extensive assortments of home and office furniture; a variety of sporting goods; and all manner of merchandise in between — sold by an in-store staff whose twin assignments are to master the merchandise and engage the customer.

So Lewis, on the occasion of its 70th anniversary, has much to celebrate. Indeed, this past May the company enjoyed the most successful month in its history. To thank the people most responsible for this performance, Griffin bought some 30 staff members lunch at the local country club. Characteristically, the chairman spent five minutes thanking his managers for their contributions, then allowed them the opportunity to enjoy their lunch. As is true for every visionary leader, he understands who’s really responsible for his company’s success.

But Mark Griffin gets much in return: the universal respect of the people who work for him — and the certainty that he has the best job in America.