Gov. Tim Walz announced a statewide mandate Wednesday requiring Minnesotans to wear face masks in stores and indoor gathering places in an effort to slow the spread of COVID-19 and prevent a second surge of hospitalizations and deaths.

When the new rule takes effect Saturday, Minnesota will join roughly 30 states that have imposed similar mask-wearing requirements in the absence of any federal act and despite sharply polarized political views.

"If we can get a 90 to 95% compliance, which we've seen the science shows, we can reduce the infection rates dramatically, which slows that spread and breaks that chain," Walz said. "This is the way, the cheapest, the most effective way for us to open up our businesses, for us to get our kids back in school, for us to keep our grandparents healthy and for us to get back that life that we all miss so much."

The rule applies to most indoor spaces outside people's homes, and to outdoor spaces where workers cannot maintain social distancing — but with caveats. Diners need to wear masks when walking around restaurants but not when eating at tables. Office workers don't need to wear them in isolated cubicles but do need to mask up on trips to the bathroom or water cooler. Children 2 and younger are exempt because of suffocation hazards, along with people with special medical conditions.

Individuals who flout the order could face petty misdemeanor fines of up to $100. Businesses that fail to comply could face misdemeanor fines of up to $1,000. Walz said the focus will be on compliance, not enforcement, and that he wants to see officers "handing out masks, not tickets."

"We're not trying to make anyone a criminal," he said. "We're trying to educate and get people to buy into this."

The state is circulating 4 million masks to local business and government organizations so people will have access to them if needed.

Trade groups for the state's doctors and hospitals have supported a mandate, along with some business leaders who didn't want to require customers to wear masks when competitors didn't.

Republican lawmakers, however, oppose it as an abuse of the peacetime emergency powers that Walz received to manage the state's pandemic response, and as an unnecessary burden in rural counties with few COVID-19 cases.

"Once again, I find myself asking why one-size-fits-all is the only option for a mask mandate," said Senate Majority Leader Paul Gazelka, R-East Gull Lake. "Businesses and individuals are already requiring and wearing masks in most situations, so the mandate feels like a heavy-handed, broad approach that won't work well for every situation."

Sen. Michelle Benson, R-Ham Lake and chairwoman of an influential health committee, challenged the governor to show the public if mask-wearing is helping and to set criteria for the mandate's end.

Walz's announcement came as the state reported an additional 507 new COVID-19 cases and four deaths — along with a positivity rate for diagnostic tests that has risen to 4.7% and indicates growing spread of the virus.

Walz said he had eyed the mandate since April but acted now to try to prevent a second surge in cases and deaths that is occurring in Southern and Western states.

"We don't want to slide backward," he said.

Mask debate continues

The new mandate came a day after a special session of the Legislature called to review the DFL governor's emergency powers, which Walz has used earlier to temporarily close schools, restaurants, and other public places. GOP efforts to end those powers failed in the Legislature, though many of the closures have been relaxed already.

The national debate over face masks continues, even as President Donald Trump has been seen wearing coverings, which he previously derided as a political statement against him. Trump recently said he is "all for masks," but he opposes making them mandatory everywhere.

Lake of the Woods County in far northern Minnesota has yet to report a positive case, and County Commissioner Joe Grund said that a mask mandate isn't necessary in his sparsely populated county.

"We've been doing what needs to be done without a mandate," he said.

Hannah Peura, owner of the Compass Rose gift shop in Bemidji, supported the mandate because, she said, "It helps level the playing field for businesses."

Survey results released Thursday by the University of Chicago showed that politics was a strong divider over mask-wearing. While 84% of Democrats backed mask mandates, support dropped to 47% among Republicans and 39% among Trump supporters.

While videos of public confrontations have become a staple of social media, Walz said he hopes the mandate will take the pressure off individuals and businesses to enforce safe practices.

"We don't want to escalate these," Walz said. "We don't want someone to accidentally get famous on the internet because they throw a tantrum at Trader Joe's."

'Good, but not perfect'

Many studies have provided only weak or inconclusive findings on the benefits of mask-wearing in public, but the evidence is building that the practice at least provides "source control," meaning that wearers protect others from germs they spread in the air through coughing, talking or breathing.

A study published in Health Affairs in June showed steeper declines in the spread of COVID-19 in states with mandates. The U.S. Centers for Disease Control and Prevention last week advised that people wear masks and highlighted a case study in which two hairdressers with COVID-19 wore masks and didn't infect any of their 139 clients.

Masks are "good but not perfect" and will work if most people wear them, maintain social distancing and wash their hands, said Dr. Dimitri Drekonja, a University of Minnesota infectious disease specialist.

"Seat belts and air bags — they work but they do not always work," he said. "Condoms, they also do not work all the time but everybody uses them and they have huge effect [in reducing sexually transmitted infections]. So masking is really like that."

Twenty-five states already had sweeping public mandates before Wednesday, when Minnesota, Indiana and Ohio all announced mask requirements. Five others have limited mandates that apply only in government buildings or in counties with high COVID-19 case rates.

Mask requirements already had been imposed in the Minnesota cities of Minneapolis, St. Paul, Rochester, Duluth, Mankato and St. Cloud.

States with full or partial mandates are led by 23 Democrat governors and 10 Republicans.

Minnesota's mandate does not go as far as those in other states with broader outdoor requirements. New Mexico's mandate applies to walking outdoors or exercising indoors, for example.

A Goldman Sachs analysis estimated that a mandate would cause a 25 percentage point increase in mask-wearing, which could have an economic benefit of keeping businesses open and preventing employees from getting sick and missing work, said Steve Grove, state economic development commissioner.

"No business wants to be the next hot spot for COVID-19," he said.

That same Goldman Sachs analysis surprised Walz when it showed that Minnesota had a lower percentage of people indicating they "always" wear masks and a higher percentage than most states of people who said they "never" wear them.

Walz said he suspects the mood has changed now that there is more evidence supporting mask-wearing and more GOP leaders such as the governor of Indiana are enacting mandates. The recent support from the president could encourage more compliance, too.

"President Trump is telling you to wear a mask," Walz said. "You've got the clearance. Go right ahead."

Staff writer Mary Lynn Smith contributed to this report.