Colorado and Arkansas have joined a growing list of US states requiring face coverings in public places to combat a surge in coronavirus infections after Georgia's governor moved the other way and barred such measures from being imposed at the local level.
With announcements from Colorado Governor Jared Polis, a Democrat, and Arkansas Governor Asa Hutchinson, a Republican, a majority of states - 26 out of 50 - have now sided with public health experts urging face masks be mandatory rather than a personal choice.
Bucking the trend, Georgia's Republican governor, Brian Kemp, issued an executive order late on Wednesday suspending local face mask regulations while saying residents were "strongly encouraged" to wear them.
He suggested an order mandating masks would be too restrictive.
After Mayor Keisha Lance Bottoms of Atlanta, Georgia's capital and largest city, said she planned to defy Kemp's order and enforce a mandatory mask ordinance she issued on July 8, Kemp announced on Thursday he had filed suit to override her.
"This lawsuit is on behalf of the Atlanta business owners and their hard-working employees who are struggling to survive during these difficult times," Kemp said. "I refuse to sit back and watch as disastrous policies threaten the lives and livelihoods of our citizens."
Earlier, Savannah Mayor Van Johnson, who issued a mask mandate in his Georgia city on July 1, tweeted that Kemp's order demonstrated he "does not give a damn about us".
Coronavirus cases have spiked across the American south and west since local officials started loosening economic and social restrictions aimed at slowing the spread of the virus.
On Thursday, Florida, Texas and South Carolina each reported a record number of COVID-19 deaths for a single day - 156, 129 and 72, respectively.
At least three other states hit a record high in the number of new infections reported in the past 24 hours - Nevada with 1447, Mississippi with 1230 and Oregon with 429.
Thirty states have registered record daily increases in confirmed cases this month, many of them more than once, and 14 states have reported a greater number of deaths for a single day in July than ever before.
Masks have become a politicised issue, with President Donald Trump at odds with the advice of his own health officials, wearing a mask in public only once.
Trump is seeking re-election in November but faces mounting criticism - and falling poll numbers - over his handling of the pandemic, including from within his own party.
Maryland Governor Larry Hogan, a Republican who chairs the National Governors Association, slammed Trump's coronavirus response in a Washington Post opinion piece. Hogan described how states scrambled to get help on testing, only to have Trump declare in April it was not the federal government's problem.
"It was hopeless, waiting around for him. Governors were being told that we were on our own. It was sink or swim," Hogan wrote.
White House spokeswoman Kayleigh McEnany responded by saying Hogan's article was "revisionist history".