Surprisingly, however, Costco's high-wage approach actually beats Wal-Mart at its own game on many measures. BusinessWeek ran through the numbers from each company to compare Costco and Sam's Club, the Wal-Mart warehouse unit that competes directly with Costco. We found that by compensating employees generously to motivate and retain good workers, one-fifth of whom are unionized, Costco gets lower turnover and higher productivity. Combined with a smart business strategy that sells a mix of higher-margin products to more affluent customers, Costco actually keeps its labor costs lower than Wal-Mart's as a percentage of sales, and its 68,000 hourly workers in the U.S. sell more per square foot. Put another way, the 102,000 Sam's employees in the U.S. generated some $35 billion in sales last year, while Costco did $34 billion with one-third fewer employees. {o's emphasis}