<P> Also in 1988, the first Wal - Mart Supercenter was opened in Washington, Missouri . The supercenter concept features everything contained in an average Walmart discount store, in addition to a tire and oil change shop, optical center, one - hour photo processing lab, portrait studio, and numerous alcove shops such as banks, cellular telephone stores, hair and nail salons, video rental stores, and fast food outlets . </P> <P> By 1988, Wal - Mart was the most profitable retailer in the United States, though it did not outsell K - Mart and Sears in terms of value of items purchased until late 1990 or early 1991 . </P> <P> By 1988, Walmart was operating in 27 states, having expanded into Arizona, Michigan, Ohio, West Virginia, New Jersey, and Wyoming . By 1990, they expanded into California (which marked Walmart officially becoming a fully nationwide retailer), Nevada, North Dakota, Pennsylvania, South Dakota, and Utah . The Walmart Visitor's Center also opened this year on the site of Sam Walton's original store . </P> <P> The 1990s saw an era of furious growth on an unprecedented scale and the incorporation of several new ideas and technology into the business . </P>

When did the first walmart open in california