Walmart Inc. /zigman2/quotes/207374728/composite WMT -1.02% announced Wednesday that face coverings will be required at all U.S. stores and Sam's Club warehouses starting July 20. Face coverings were already required at 65% of locations in cities and towns where there was a face covering government mandate. The company has more than 5,000 stores and clubs in the U.S. The five days will be used to alert customers, post signs and train workers on new protocols, according to a blog post by Dacona Smith, chief operating officer of Walmart U.S., and Lance de la Rosa, chief operating officer of Sam's Club. Walmart has also created a new role, health ambassador, who will receive special training to alert customers of the rule and find ways to resolve issues that arise from those who refuse to wear a mask or cannot wear one. Sam's Club will provide a mask to members who don't have one at no charge. All stores will also have a single entrance to ensure consistency. "We know some people have differing opinions on this topic. We also recognize the role we can play to help protect the health and well-being of the communities we serve by following the evolving guidance of health officials like the CDC," the blog post said. Starbucks Corp. /zigman2/quotes/207508890/composite SBUX -2.07% is among the other companies that are now mandating a face covering to enter one of its locations. Walmart stock has gained more than 16% for the year to date while the Dow Jones Industrial Average /zigman2/quotes/210598065/realtime DJIA -0.88% is down 5.4% for the period.