(CNN) -- A growing number of US states have mandated the use of masks and face coverings while in public.
With many states starting to lift coronavirus restrictions, more people are venturing out in public, but the number of cases is still rising in nearly half of them.
That's where masks come in. A recent study found that the use of masks and face coverings has been the most effective way to reduce person-to-person spread of coronavirus.
Here are the states that require the use of masks or face coverings in public settings.
As of June 18:
California Gov. Gavin Newsom issued a statewide order on Thursday requiring the use of face coverings in public indoor spaces, including while shopping, riding on public transportation or seeking medical care.
Newsom's order also mandated the use of masks or face coverings in public outdoor spaces when social distancing is not an option. There was no guidance on how the order will be enforced or if violators will face any penalties or citations.
As of April 20:
Connecticut's mask requirement applies to any resident over the age of 2 in a public space where social distancing isn't possible. The rules also apply to individuals using public transportation, taxis or rideshare services.
The state's Department of Economic and Community Development also released mask guidelines for essential workers:
Employees at essential businesses must wear masks or any other material covering their mouth and nose at all times while at work. Employers must provide masks or the materials to make them. All customers under age 2 must wear them, too.
People who refuse to wear masks aren't required to provide proof that they're medically exempt.
As of April 28:
Delaware Gov. John Carney ordered residents to wear face masks while in public, including at grocery and convenience stores, pharmacies, doctor's offices and on public transportation.
Children under the age of 12 are not required to wear face coverings, and those age 2 and under must not wear face masks due to the risk of suffocation.
District of Columbia
As of May 16:
District of Columbia Mayor Muriel Bowser ordered the use of masks or face coverings when conducting essential business or travel and social distancing isn't possible.
Masks or other face coverings are required in grocery stores, pharmacies and takeout restaurants. On public transportation, face coverings are required if individuals are unable to be six feet apart.
Children between the ages of 2 and 9 are advised to wear masks.
As of April 20:
Both customers and employees at essential businesses are required to wear cloth face coverings. Establishments must limit the number of customers allowed in and keep them six feet apart.
Anyone who violates those rules could face a fine of up to $5,000, or up to a year in prison if found guilty, according to Hawaii Gov. David Ige's order.
As of May 1:
Illinois Gov. JB Pritzker ordered the use of face masks for anyone stepping outside their house.
Face coverings are required while shopping at essential businesses, traveling on public transportation, picking up food, or visiting the doctor and it's impossible to stay six feet apart.
As of May 11:
Kentucky Gov. Andy Beshear ordered all state residents to wear face masks in public.
Gov. Beshear has said that people will not be fined or arrested for not wearing a mask in public, but the order gives businesses the right to turn away any customer not wearing a face covering.
As of May 1:
Maine Gov. Janet Mills issued an order requiring face coverings or masks for anyone over the age of 2 in indoor public spaces such as supermarkets, retail stores, pharmacies and doctor's offices.
As of April 18:
Commuters must wear face coverings while using Maryland's public transit, according to Gov. Larry Hogan's order.
Employees of essential businesses and customers over the age 9 must wear face coverings. Adults accompanying young children should make an effort to get them to wear a mask.
As of May 6:
Massachusetts Gov. Charlie Baker issued an order requiring the use of face coverings or masks in both indoor and outdoor spaces where social distancing isn't possible.
Children under the age of 2 do not have to adhere to this order.
As of June 18:
Michigan requires all residents to wear face coverings or masks in all public settings.
Businesses are allowed to deny entry to individuals not wearing face coverings.
As of June 24:
Nevada requires anyone in any public space to wear a mask. Nevada Governor Steve Sisolak's office said this includes while using public transportation, in public facing work environments, while patronizing businesses, or interacting with others in any generally publicly accessible space.
"For Nevada to stay safe and stay open, we must make face coverings a routine part of our daily life," Sisolak said.
As of April 8:
New Jersey was the first state to require customers and employees to wear face coverings at essential businesses and construction sites. Businesses must provide them to employees and deny entry to any customer who refuse to wear them (though customers can still pick up food or medicines in other contact-free ways).
Commuters on New Jersey's trains, buses and light rails must wear face coverings. If they refuse, they may be denied entry.
As of May 16:
Adults are required to wear masks in all public settings, except while eating, drinking, exercising or for medical reasons. Masks are recommended for children 3 and older, and children 5 and under must have adult supervision.
As of April 17:
New York Gov. Andrew Cuomo's executive order mandated state residents to wear masks in public.
All residents over age 2 must wear masks or face coverings when in public and social distancing is impossible.
As of April 19:
Essential businesses must provide and require their employees to wear masks, according to the order from Pennsylvania's Department of Health. Customers at these businesses must wear masks while on the premises or be denied entry.
As of May 8:
Gov. Gina Raimondo issued an order requiring all residents over the age of 2 to wear face coverings or masks while in public settings, whether indoors or outdoors.
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