Large retail chains have started requiring customers to wear masks inside all their stores, as coronavirus cases surge across the country and politicians and public health experts clamor for widespread use of face coverings to stem the spread of the disease.

After Walmart, America’s largest retailer, announced July 15 that it would mandate in-store mask-wearing, a flurry of other companies, including Kroger, Target and Walgreens, followed suit. This means that customers will be required to wear face masks in stores even in places without local mask ordinances. The National Retail Federation has encouraged companies to set nationwide mask policies to protect employees and shoppers.

Some chains, however, have moved in the opposite direction. After implementing a customer mask requirement nearly two weeks ago, Dollar Tree and Family Dollar reversed course on Monday, saying they would require masks only if mandated by state or local rules.

Here is a list of the major retailers that have told customers they must mask up.

>>Apple: On May 17, the iPhone maker announced that all shoppers would be required to wear masks inside its stores. The company said it would give masks to customers who did not have them.

>> AT&T: On July 2, AT&T announced that store visitors needed to wear face coverings. The satellite communications provider also said it would provide masks to customers who need them.

>> Bed Bath & Beyond: The home goods retailer, with over 1,460 locations across the United States, Mexico and Canada, said it would require all in-store shoppers to wear a mask beginning Friday.

>>Best Buy: The electronics company said July 14 that all customers must wear face coverings when shopping in Best Buy stores. The company will provide masks to customers who do not have one. The policy, which went into effect July 15, does not apply to small children or people unable to wear a mask for health reasons.

>> Costco:On May 4, the wholesale outlet mandated that shoppers wear a mask covering both their nose and mouth at all times, excluding children under age 2 or people unable to wear a mask because of a medical condition.

>> CVS Health: Jon Roberts, chief operating officer of CVS Health, said July 16 that the drugstore chain would require all customers to wear face coverings while shopping in-store, effective July 20. “To be clear, we’re not asking our store employees to play the role of enforcer,” Roberts said in a statement. “What we are asking is that customers help protect themselves and those around them by listening to the experts and heeding the call to wear a face covering.”

>> Gap Inc.: The clothing retailer, which operates its namesake brand Gap as well as Old Navy, Athleta, Banana Republic, Intermix, and Janie and Jack, said Monday that customers must wear masks in all its stores in North America, effective Aug. 1. The company will provide disposable masks to patrons who need them.

>> Home Depot: The largest home-improvement retailer in the United States announced July 17 that patrons will have to wear face coverings inside all its stores starting Wednesday. Small children or those with a medical condition preventing mask-wearing are exempt from the policy. “Social distancing captains” will provide masks to shoppers who do not bring their own, according to a company statement.

>> Lowe’s: The home improvement company said July 17 that shoppers must wear masks or facial coverings in Lowe’s stores nationwide starting July 20. The company is offering free masks to customers while supplies last.

>> Starbucks: The coffee chain announced July 9 that customers must wear face coverings while visiting all Starbucks locations in the United States, a mandate that began July 15.

>> Target: On July 16, Target said customers have to wear face masks at all stores nationwide, effective Aug. 1. The Minneapolis-based retailer will provide disposable masks to guests who do not have one.

>> Verizon: The phone service provider said May 18 that all customers are required to wear cloth face coverings when visiting Verizon stores.

>> Walgreens: On July 16, the Deerfield, Illinois-based company announced that all customers have to wear face coverings while shopping, effective Monday.

>> Walmart: Walmart, which operates more than 5,000 stores in the United States, mandated July 15 that all shoppers wear face coverings, effective July 20. The company will station a “health ambassador” at store entrances to remind customers to wear a mask. Sam’s Club, which is owned by Walmart, also requires customers to wear face coverings and will provide masks to customers who need them. “We know some people have differing opinions on this topic,” Walmart said in a statement. “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.”

>> Whole Foods Market: Effective Monday, the upscale supermarket brand owned by Amazon required customers to wear face coverings while shopping. Whole Foods Market said it would provide masks at the entrance of all stores to customers who do not have their own face covering.