Pennsylvania officials announced Wednesday that residents must wear face coverings when outside the home, the latest in a series of statewide mask mandates to combat the spread of COVID-19.

The order takes effect immediately, and builds on an April directive requiring masks to be worn inside businesses. Gov. Tom Wolf called the expanded measure essential to stopping the recent increase in coronavirus cases reported in the state.

"Those hot spots can be traced to situations where Pennsylvanians were not wearing masks or practicing social distancing — two practices that must be adhered to if we want to maintain the freedoms we have in place under our reopening," he said.

Pennsylvania is not the only state to make such an announcement in recent days.

On Monday, Oregon Gov. Kate Brown announced that a mandate requiring face coverings in indoor public spaces that previously applied only to certain counties would take effect statewide on Wednesday. And in Kansas, masks must be worn in indoor public spaces, as well as in outdoor settings where social distancing cannot be maintained, starting Friday.

"Wearing a mask is not only safe — but it is necessary to avoid another shut down," said Kansas Gov. Laura Kelly.

The growing list of states with universal mask mandates includes North Carolina, California, Nevada, Rhode Island, New York, Delaware, Connecticut, New Mexico, Illinois and Washington.

Other states have rules in place requiring people to wear masks in certain situations, like on public transit or in grocery stores. And in some parts of the country, local governments — such as Phoenix and Jacksonville, Fla. — have enacted mandates of their own.

Official health guidance recommends wearing cloth face coverings to help prevent the spread of respiratory droplets that travel into the air and onto other people as a result of coughing, sneezing or speaking. Research supports the efficacy of masks in controlling the spread of the virus.

"There's no doubt that wearing masks protects you," Dr. Anthony Fauci, the nation's top infectious disease expert, told members of Congress on Tuesday.

While mask usage has been the subject of partisan debate, leading Republicans such as Vice President Pence, Senate Majority Leader Mitch McConnell and House Minority Leader Kevin McCarthy have been newly vocal in expressing their support for face coverings in recent days.

Other officials, like presumptive Democratic nominee Joe Biden and House Speaker Nancy Pelosi, are advocating for a federal mask mandate.

"When you do not wear your face covering, we end up in a situation where you see higher rates of disease spread and you end up having to close places," Surgeon General Jerome Adams said at a public briefing on Tuesday. "This mask, this face covering, actually is an instrument of freedom for Americans if we all use it."

According to new research by Goldman Sachs, a national mask mandate could save nearly 5% of gross domestic product, in addition to cutting the daily growth rate of confirmed coronavirus cases to just 0.6%.

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