(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.
California
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.
Connecticut
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.
Delaware
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.
Hawaii
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.
Illinois
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.
Kansas
As of July 3:
An executive order was issued by Kansas Gov. Laura Kelly mandating face masks must be worn statewide in public spaces.
Kelly, commenting on Facebook Monday, wrote, "Starting July 3, I will issue an Executive Order requiring marks be worn in indoor public spaces, and at any outdoor gathering in which social distancing cannot be maintained. This step will keep Kansans healthy, and keep Kansas open for business."
Kentucky
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.
Louisiana
As of July 13:
Louisiana Gov. John Bel Edwards announced a statewide mask order for everyone 8 years and older.
Parishes in the state can opt out of the mask mandate if they don't have a high positivity rate, but Edwards said only three would qualify to do so right now.
Maine
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.
Maryland
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.
Massachusetts
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.
Michigan
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.
Nevada
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.
New Jersey
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.
New Mexico
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.
New York
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.
North Carolina
As of June 26:
North Carolina Gov. Roy Cooper requires that face coverings be worn whenever people are out and about in public and where physical distancing is not possible. A number of businesses, such as restaurants and hair salons, also will require both employees and customers wear face masks.
"We need to all work together so we can protect our families and neighbors, restore our economy, and get people back to work and our children back to school," Cooper said in announcing the requirement.
Oregon
As of July 1:
Oregon Gov. Kate Brown has now required the state's residents to wear face coverings in all indoor public spaces beginning July 1. Face covering requirements are already mandated in eight counties but this would broaden the mandate to the whole state.
"I do not want to have to close down businesses again like other states are now doing," Brown said in a statement.
"If you want your local shops and restaurants to stay open, then wear a face covering when out in public," she added.
Pennsylvania
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.
Puerto Rico
People are required to wear face coverings when in public spaces. Businesses must ensure customers are wearing face coverings.
Rhode Island
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.
Texas
As of July 3:
Gov. Greg Abbott issued an executive order that will require residents in counties with 20 or more active Covid-19 cases to wear face coverings in public. It takes effect midday on July 3.
The order says that failure to comply could be punishable by a fine.
Virginia
As of May 29:
Virginia Gov. Ralph Northam instituted a statewide mask mandate that requires residents aged 10 and older to wear a mask when entering or spending time in establishments such as restaurants, grocery stores and train stations.
Washington
As of June 26:
Washington Gov. Jay Inslee instituted a mask mandate that requires everyone to wear a mask or face covering in an indoor public space and in outdoor public spaces where social distancing isn't possible.
West Virginia
As of July 6:
West Virginia Gov. Jim Justice issued an executive order that he said would require all West Virginians 9 years old and up to wear a face mask anytime they are in public and indoors and where they are unable to maintain six feet of social distancing.
Justice said he issued the order after the state experienced its highest daily total of new cases over the July 4th weekend.
"I know it's an inconvenience, but it's not going to be much of an inconvenience," Justice said. "If you don't decide to wear the face covering for yourself, if you don't decide to wear it for one of your loved ones or your friends, do it for the 95 West Virginians that have died, do it for the 95 people that we've lost."
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