The world's largest retailer on Wednesday said customers must wear face coverings in their stores from July 20 onward.

In a Wednesday announcement, Walmart said about 65% of its over 5,000 U.S. stores - including Sam's Club - are located in areas where there is already some form of government mandate on face coverings.

Now, the company is following suit at all of its U.S. stores - regardless of local rules - as cases of coronavirus soar across the U.S.

The company said it will have 'Health Ambassadors' - stationed at the entrance of Walmart and Sam's Club stores to remind customers of its new policy.

While acknowledging that some people have different opinions on wearing masks, Walmart said "The ambassadors, identifiable by their black polo shirts, will work with customers who show up at a store without a face covering to try and find a solution."

Also on Wednesday, policies went into effect at Starbucks and Best Buy stores nationwide - requiring customers to wear face coverings at all times.

Health officials are urging widespread action.

CDC Director Robert Redfield on Tuesday said that if all Americans wore a mask, the rising cases of COVID-19 could be under control in four to eight weeks.